My opinion: Let's keep the General Arranger Synthzone family together.
Since the internet community already has quite a few good Tyros dedicated message board forums out there already: Tyros2.net, SVPWorld, PSRTutorial, Tyros Yahoo Groups, just to name a few, I'm not sure I see the benefit of limiting the SZ 'Yamaha forum' to Tyros2 discussion only.
Because Yamaha keyboards (from PSR2000 to Tyros2) share the SAME basic core OS, discussions/questions/answers about one model may be equally beneficial to people who own & play other Yamaha models too, of of would be missed by them.
I particularly enjoy the Synthzone General Arranger forum for it's colorfully diverse membership, debate & discussion of ALL brands/model keyboards, as well as just hanging out with all the friends (Yamaha, Ketron, Korg, Roland, GEM, Casio, etc alike) I've met over my 5+ years on the General Arranger forum. Though I play a Yamaha Tyros today, I always remain open to adding another brand/model arranger.
Lastly, religating Tyros2 talk to the Yamaha forum may keep me from being able to express my enthusiam for Tyros2 here, though I suspect some here will find that a tremendous relief. - Scott