If one thinks about it there are $200 firearms with sturdier barrel fastening methods and steel receivers.
The receiver on my Mac1 USFT PCP is thicker than any firearm I own, though it's aluminium.
It's only the mentality of building frailty into PCP's that needs to change. Imo, it's better to sacrifice lightness for a little more weight by having a steel receiver and a superior way of fastening the barrel. Also lose the flimsy shrouds, liners, and barrel bands.
Btw' the worst shifting I've had was with the barrel band in my steyr lg100. Hard to describe but it's part of the receiver about a foot down the barrel. Once free floated the poi shifts were gone.
I was amazed coming into the airgun world the design decisions these manufacturers were making. Completely counter to what the powder burner world does, and often to the detriment of precision.
We've known each other for years now on that other forum and I think both of us are pretty familiar with most of the firearm rifle receiver designs and the various ways of barrel attachment. A shouldered barrel that's torqued to 80+fp like you mentioned is probably the most trouble free way to go but I think other ways would work 99% as well for AG's. A few that come to mind are #1, the way Accuracy International/AI does theirs in the AT. It's fast and easy to remove a barrel and replace with another in minutes and it's a solid way of fastening it. The other one is similar and it's the Desert Tech way of fastening a barrel.
The PCP receivers should have a longer and thicker area to support the barrel and be made more rigid in general.
I've never liked that most PCP's attach to the stock with one screw!!!!!! Two screws holding the receiver to the stock keeps the action from moving around in the stock less and pillars with glass bedding would help too.
Heck on a PCP rifle the barrel doesn't necessarily need to be threaded because the recoil and pressure is so low, it just needs a solid and strong way to be held by the receiver and a way to key it to the same location.
The barrels, they could stand to be a little thicker. If we look at the how thick a cheap 22rf barrel sporter barrel is it's usually much thicker - more rigid. It's also very rare to see great quality barrels in the PCP world. It would be awesome to see Bartlein, Krieger, and other higher end barrels as a purchase option!
I like the way the FX Impact is designed in respect to it's mid length cocking lever, that's the main reason I bought it as well as the high capacity mag. I absolutely hate that stupid finger knob holding the barrel, lol, what were they thinking???!!! It's a cool rifle in a lot of ways but a head scratcher in other ways.
My old FX400 is a pretty solid PCP. No barrel bands or shrouds, I like it for the most part.
My USFT is a crazy overbuilt and simple rifle, lacking a reg to fail, and is probably the pinnacle of reliability in the PCP world.
Here's the link to a video where Ed himself, with his Land Cruiser, demonstrates the ultimate meaning of "truck gun." 
