I'll hope in once more. The older Shadow 1000 is, IMHO, really NOT that bad a gun. Give it a lube tune. Charlie's trigger and you have a pretty decent rifle capable of hunting or informal target shooting. If the synthetic stock bothers you (and I happen to prefer it on that one), you can always remove the buttpad and fill it with whatever you like - rags, spray foam, high density (couch cushion) foam, you name it. The 220/440/890/Hunter are all the same gun, just different wood stocks and trim. For the money, a tuned older Gamo is hard to beat.
As to the new Gamo's, well, the jury is out until the trigger change is settled. Charlie looked at a new one and opined that there was nothing worth doing to it - in other words, you're stuck with the factory unit. And they changed some internals, too, so a gas ram drop-in might not work, either. If I were in the market for a Gamo break barrel, I would be looking used and older style. There have to be about a million of them out there in one form or another.
The Nitro piston or NPSS is a good idea, but it is not Crosman's. Give credit to Theoben for that one. What I would like to see is a ram for the Nitro that is adjustable as to fill level. Then you could tune the gun up or down for hunting/indoor shooting by adjusting the pressure. I think Theobens might have this feature. Somebody's ram did. I like the Nitro but, apparently, it will need a $45 trigger from Airguns of Arizona to make it better. Some do it yourself mods out there but what can beat a drop in? Methinks Charlie is secretly in the laboratory as I type, so, if you have a Nitro, hold off on the AoA unit. Support your local sheriff. And the Nitro is not a light weight like the Gamo with synthetic stock. I picked up a .22 combo and it was pretty solid. Don't know how that stock style would feel after carrying it for three or four hours. Conventional stocks are pretty easy to cradle or throw over your shoulder.
As to the CFX, if I were doing nothing but buying a gun and maybe lube tuning it, that would be it, plus Charlie's trigger. Hey, I did that. Bought Gene's .22 Royal which is stock except for the light tune/trigger and it is really nice to shoot. Adequate power and accuracy.
Bottom line is, get a gun you will enjoy. Doesn't matter if it is Gamo, Turkish, Mexican, German, UK or Chinese. What I've come to find out is that air guns are a very personal choice - more so than firearms.