+1
AFAIK Cobb have not and are not releaseing an AP for the 370z, so that kindof points to the fact that they will be stopping development of AP. Added to this, as Ian says, I havent heard of a UK car using it, and on the US sites, they dont state it will work on JDM or UKDM cars.
UpRev have invested heavily in getting reflashes working on the 350z and the 370z and also getting it working on UK cars, so for me that is definately the way to go
Abbey and RS Tuning are both forum traders and official UpRev tuners.