To give some context, I have an FX Impact X 25 cal shooting 34g JSB at 905fps for around 60fpe. I also have a 357/9mm W.A.R Flex shooting 81gr pellets at 910fps for 150fpe, to shooting 120/140gr NSA slugs at 200+fpe. The W.A.R Flex is built like a tank, just look at the chassis, bolt probe, bottle block, regulator, tensioned barrel, shroud, etc... I have been shooting the 357 Flex for almost 2 years without any issues, it takes the recoil and stresses of 150-200+fpe like a champ. I can't confidently say that the 35 cal Impact , if released as is, will be able to handle the stresses of 150+fpe without FX beefing it up around these weak points:
1) pellet probe and its retaining screw(known issue even for smaller calibers, imagine having 150fpe stressing it)
2) barrel retaining screw and floating barrel design
3) additional valve and regulator upgrades
I think FX will need some major work to shoot 35 cal. The only pellet that currently fits is the JSB 81gr, which is short enough. The 35 cal polymags and NSA slugs all won't fit into the breech due to length. Is FX going to cut and extend the breech opening? If they do, it will change the existing dynamics of the Impact, by then you will have a 35 cal impact that differs from other caliber impacts...
I am rooting for the Impact 35 cal, because i can then share some 35 cal ammo between my Flex and Impact. But i am not holding my breadth for it, and when it does release, unless it is beefed up significantly, i won't be the guinea pig tester for it given the known weak points even with current smaller calibers.