> But will developers/users really flock to Opera just because it has a fast JIT? For me, Opera is just something to check for compliance.

I think it's the reverse: users will like Opera if it has UI features they like. It's highly unlikely that Opera would be able to beat Chrome / Safari on speed but there's plenty of room for innovation in other areas now that the web is becoming fast enough for most users.

Not having to support a modern browser engine just be able to start those features is the major win for Opera because they can focus on things users actually care about rather than obscure feature compatibility or baseline competitive performance.