What? 1.2bar of boost isn't max on standard engine. There are loads of coupes running 1.4 - 1.5 boost on standard internals without issues mine being one of them - 3 years without problems...
Yes, but 1.5 bar on a GT2871 will give around 400bhp, 375lb-ft and several bent conrods
1.5 bar is OK on a small turbo (with sufficient other mods), but not with something like a GT2871
Some people have got away with it, but IMHO, they're driving a grenade
At the end of the day, if the power figures between two cars is identical, 1.2 bar using a GT2871 is better than 1.5 bar on a hybrid