Nex 7 - 16-50 f2.8 vs 16-80 CZ A mount?

Thanks to all here, I'm going out to buy the LA-EA2 tomorrow, finally decide I will trade off th IS for the faster zoom.

Will also pick up a lens, please help me decide!

16-50 2.8, faster, constant but bigger and shorter range

16-80 CZ 3.5-4.5, good size and weight, better range, but a bit slow at the tele.

If price were similar, what would you choose to use with the Nex 7 and the A mount adapter?

Thanks!