[Tinwarble]

thanks @hdmkv and @ned scott - you think the 500gb pro model is necessary?

No. I have both, and with recent Android M and being able to treat mSD card as part of internal storage almost makes the 500GB version unnecessary. Unless you want to put a lot of games and ROM's on the internal drive. Even then, a large mSD should perform as well I'd think.

Yep, with adoptable storage that was add with the 3.0 (Marshmallow) update you really don't need the 500GB model.

And if you need more storage than a microSD can give you then you can also adopt a USB HDD or SSD. When I first setup adoptable storage I was using a 500GB HDD on one of SATVs, but because I didn't care for having a spinning drive as adopted storage I switched it out for a 128GB USB 3.0 thumbdrive. But I'm probably going to swap that out for a 200+GB SSD later.