Well JDM_GT, it seems I've already proved you right haha...
After all my procrastination about my turbo a few months ago, and 'deciding' that I would keep my GT3082R, I've ended up changing my mind after a few long discussions with MRC and researching all over the web.
I'm strongly considering changing the turbo, and right now I'm thinking Precision 6262 ball bearing turbo with 0.82 A/R hot side.
MRC said last week with the GT3082R they were struggling to get more than about 273rwkw at ~23psi without knocking (on MRC's Mainline dyno which does read slightly lower than their previous Dyno Dynamics). I think the main problem is that the exhaust side of the turbo is a bit too small/marginal for my goals, and it is known to be a mismatch when mated to the big 82mm compressor anyway.
I'm making the change now before getting the full dyno tune and then later wishing that I had changed the turbo. Of course I will now have to wait a few more weeks to get my car back, but I can live with that.