Thank you for all the input so far,
the main note I'm getting, from my perspective, is that i've left the other players under-equiped relative to how far along the game is. They've spent most of their time on frontier low-tech systems/worlds so i've clamped down on what's 'impossible' to aquire and maybe been to stingy on oppertunities to roll aquisition tests. The one thing i don't really understand though is the comparisons to the heavy bolter; the heavy bolter does 2d10+2 damage with 5 pen (so, since there's very few targets with total AP lower than 5, essentially 2d10+7 before armour reduction), with tearing quality. The range of damage therefore is 9 - 27, with an average of somewhat above 18 due to tearing. Storm of force, according to the errata 1.4(which as far as I know is the latest), does 2d10+ 3PR, not x2. currently my astropath player's PR is 7 and can push to 11 thanks to warp conduit. using 7: 2d10+(3*7 =) 21, for a range of 23 - 41, average 32. using 11: 2d10+(3*11=) 33, for a range of 35 - 53, average 44 While it can land more than one hit on a target, the heavy bolter also has a limited firing arc. If I try to use flanks of surprise, the storm of force just creates an absolute deathzone in a huge area around the Astropath The rest of the group is comprised of -Missionary with a buffing and melee focus -An archmilitant focusing on accurate-type weapons/building to be a 'sniper' -An explorator who wanted to go for an odd build and focus on agility. Between high dodge skill and typical techpriest AP she's the 'trap-spounge' of the group. Offensively pretty much just carries a heavy weapon for suppressing fire.
The only other factors I can really think to mention is maybe some blame could be put on the group's tactics (they tend to just scatter to the nearest cover in combat, even if its the weakest, rather than try to pull into narrow cooridors for the explorator to hose them down or the sniper having room to kite), and my Astropath being peternaturally lucky with phenomenon/perils, which is maybe skewing my perspective of how dangerous psi powers are to use. From what I've learned from all your posts, it seems like the best option is to look for ways to get the others more on-par using equipment, then seriously up the power of the enemies I throw at the group.