On-the-fly adjustable power .22 PCP, What's out there?

It's above 1k but the Impact is going to be the most adjustable gun you can get. 

The very nature of the adjustability raises the price. They require extra o-rings and tighter tolerances. That's why you can either get a good price or a lot of adjustability. 

get an aa s510. its the best of the bunch

My Brocock has the big tank, but the smaller tank compatto is cheaper. It's my favorite, right sized. I have an S510 that's fine too, but bigger.
talon was a disappointment, high air consumption and single shot, ugh
I have good luck with FX and you should consider a streamline, low air consumption on medium power 

Yeah, that's where my mind went, FX Streamline. Three step power adjuster. Has everything you want except the bullpup design. Light, not too long (40"). Although, to quiet it down you'll need to add a couple of inches for the moderator. 

Smaug, do not get the Talon SS. I have one and not very impressed. Accuracy is so so despite having a Walther barrel. Power wheel doesn't do much. 
I would recommend an Air Arms S500 instead of the 510 if trying to stay under 1K. Perfect for what you want to do. Mine are super accurate and I have two, one in 0.177 and 0.22. I can drop the 0.177 power to 7 ft lbs or increase up to 20 ft lbs with the right pellet. Don't miss the magazines at all. Easy to top off with a pump. Trouble free since I bought them over a year ago. 
If you want to add a moderator in addition to the shroud, go with the S500 carbine to keep the overall length down. Let me know if you have any other questions. 

Also, just as an FYI, I know you mentioned on the fly adjustable power. In an ideal world, you could get away with one accurate pellet and just turn the power wheel up or down. However, I've noticed on my Air Arms S500 in 0.177 that certain pellets like different velocities. I can shoot an RWS Superdome at 7 ft lbs very well at the lowest power setting. But if I crank up the velocity, accuracy goes to hell. Other pellets like the JSB like faster velocities and my accuracy goes to hell on lower power. Also, POI shifts dramatically as you mess with the power so be ready for scope changes and re-zeroing a lot. 

The Mutant is extremely adjustable. I have the standard, and it is also a tack driver. I asked Ernest about it before buying one, and he described it as "infinitely adjustable". I have mine set to 12 ft/lbs for backyard pest control, but just by turning up the hammer spring a certain number of turns, it's at 30 ft/lbs that quick. I've only shot the 18 gr JSBs, but it can push them out at almost 1000 fps (too fast obviously), but it should shot heavier pellets at reasonable speeds.

The hammer spring adjustment is right on the back of the gun. It's a flat plug that has 2 holes, and you're supposed to insert 2 supplied rods to adjust it. I took a brass rod that fit the holes and bent it into a U shape so it would stay in via friction. I just leave it in all the time and can adjust the power very quickly. Pair that with a chrony and you can dial in pretty much any velocity you want for any pellet.

Can't say enough good things about my Mutant. Bought mine from Charlie Frear at Georgia Airguns, and he's a great guy to deal with.

Oh, and it is mouse fart quiet at 12 ft/lbs and very backyard friendly even at 30.

Travis from WAR is going to offer tuned Kral Puncher Breaker Silent bullpups that he goes through to ensure no mechanical problems & makes more backyard friendly for a modest fee. It has a rheostat style power adjuster and the hammer spring can be adjusted as well. He'll also be offering a "power tune" for higher power with heavier pellets. 

http://www.gatewaytoairguns.org/GTA/index.php?topic=122431.msg1189256#msg1189256

http://airgunguild.com/pcp-c02-and-helium-powered-airguns/fixing-the-kral-silent-marine-22/

Smaug-
I was going to grab Mutant until Travis offered up tuned Kral's I bought the one posted in the link above, should have my hands on it in a couple days. I was only looking for 20-28fpe something to shoot in the yard more than my .25 as it's a little to powerful.
I figured I'd grab this tuned Kral and see how I like it, I still may get a Mutant but this may do and allow me to get a Big bore next.

Pyramydair has a refurbished AA TDR for $935.99...a moderator from Neil Clague will bring you to about $50 over 1k.

https://i.imgsafe.org/fdd685a345.jpeg

I have an AA Ultimate Sporter in .22 as well and the TDR shoots a lot better in low setting than the former. The power setting knob for both isn't readily marked "high," " medium," or "low;" you're going to have to mark areas on your stock for the setting needed at the time.

Gonna have to say FX Streamline NOT a bullpup but regulated, 190cc good for hand pumper solid 60 shots a fill 230bar with a jsb 18gr at about 863 avg fps adjustable hammer spring carefully is locktited or somethimg must warm first to loosen. Power wheel is if i recall correctly on my gun it was about 9,16 and 28ft/lbs with a 13.43jsb and totally repeatable. So even if you only pump to 200bar I am sure there with be plenty of shots at a good power of your choice. Oh and its under 6lbs in synthetic and costs 999.99.

Not much longer than my Vulcan tactic. How about a Daystate Regal XL? Very carbine in size. 160cc air tube, about as accurate of a gun as you'll find. New for under 1K, used ones in great shape $750-$850.
jk

Brilliant idea. They only sell it for right-handers here so I had to get something else. Daystate at $1k is fantastic. No regulator to screw up which, forensically speaking, is an advantage. Harper sling-shot valve is very efficient an quiet.

The Mutant is extremely adjustable and if you were to go bullpup route that's what I would do. Hard to find a better gun at any price if looks aren't that big of a deal to you.

If a rifle I would definitely look into the Daystate Regal XLs. I've been looking into them lately as a gun down the road and they seem great

Not to many choices if you want a power dial and bullpup.

Kral Puncher Breaker
Hatsan Gladius

and then above 1k

FX Impact and bobcat
Air Arms Galahad
Daystate Pulsar/renegade

thats it. Looks like its going to be turkish for you.

Sumatra carbine with LDC. It's not a bullpup but it weighs a little over 5 lbs and 35" without moderator.

my s510 air arms will go from 10 to 42 foot pounds in .22 very versatile.
​and high quality. and trust me it will be every bit as accurate as a daystate.
I ow both daystate and air arms.
get an air arms .22 s510
on a ds regal you can really change the power..