Why so many if you don't know they work yet? I mean, it's your money but...
More often than not it's misinformed people that think they have to fire at exactly 350fps (you don't) and that the groupings aren't just lack of ability (it usually is) or ignoring physics (small plastic balls, outdoors, breezes - go figure).
Nobody NEEDS to spend a crapping fortune upgrading their TM recoil. Any gun that costs £400+ should be more than capable on the field, if it isn't maybe it's the player not the gun. Or else you bought a shit gun without bothering to do any research. With regards to the reviews you've seen, if they are indeed mostly US based then you need to remember that they usually run at much higher FPS limits. As most guns are built for the Asian market (especially Tokyo Marui) they aren't set up for high power and often don't stand up well to the rigours of 400+ FPS full auto use. Hence they tend to prefer brands that DO work well in that way and will argue that G&G, TM etc are all garbage that need to be ripped apart and rebuilt with pig iron to be decent.