I might consider another bigbore at some point, mostly because I have a bunch of lead on hand and bigbores have come a long way since when I had one, but here's my experience on the subject in brief.
15 or so years ago I bought a Career 909 PCP just to see what the bigbore thing was like. I tried 115 and 124 grain cast bullets in it. 115's were in the 650 fps area and grouped 2.25" at 50Y so I settled on them. I thought that would be fine for coyotes and small game but under powered for deer, etc. It was fun hunting Jack's with it and bowled them right over.
What I didn't like was it only gave 5 good shots before it started hitting too low. It was also an air hog IMO. Back then I only had a 3000 psi tank so this turned out to be too much of a hassle to deal with so I sold it within a few months.
A few years ago I shot a 45 cal PCP that sent 230 grainers at 900 fps. it only got two shots before it was hitting low (relatively) at 50Y, but that thing hit hard!! Basically had the power of a 45ACP +P pistol load. IMO, great for hunting deer, etc, but far from a convenient plinker type of gun.
I also shot another high quality 45 PCP a few months ago, these are loud, have a lot of gun movement, and suck air like crazy! Just not my thing.
IMO, if you go down this road, and plan on shooting a decent amount, a compressor would be a "must have" unless you have a easily accessible store, etc, to get tanks filled, and owning two tanks would be helpful. No way in the world would I try to pump one of these things up unless only hunting using a few shots here and there!!!
I'm leaning towards a .257 caliber at this point because I like the high-ish BC for the weight, and don't need the energy those larger calibers give.