Have you tried the uni170 ?i'd wait for the kujira over the uni 170, the 170 is still a huge span if you want to hotdog it, my 71cm span gong HA goes rail to rail like crazy and is insanely fast, almost too fast for turns at points, i think you'll still be stuck in swoopy land on the 170 uni although that thing does pump like an absolute mofo it's still fVcking wide.
I've been using the Sig 165 (same as uni 170) and it does turn really good despite having a wingspan of 900cm. I would say a cut down flat stab is what you need to make it easier to turn, at least this is what I use. This set up is also one of the lightest in the market.
Also, I think you can't compare Gong to Uni or Sig, it would be like comaring NSP surfboard to Lost surfboard. I have many friends with Gong set up and they struggle so much (the weight, it is so woobly, screws are very low quality, etc...).