By the way, I'm directly affected by those limitations, not merely using them to pretend that some system is no good (not selling, etc.). Still, Pentax is the better choice for me.
I decided to start with the 28-105, which according to ephotozine is excellent for a "kit" zoom:
In addition, there's the DA 70mm which I'll be able to use without restrictions (or so it seems). Good; I really like that lens.
I was uninspired when I've got the DA* 60-250mm instead of the DA* 300mm, as the latter is a FF lens. But I have alternatives right now, the aforementioned DA* 300mm and the brand new D FA 150-450mm (the DA 560mm, another FF lens, is way too expensive for me).
The problem is on the wide side, there are no modern primes; one must go for older designs, or zooms. The Tamron starts from 15mm, but it's quite large and heavy and a bit overkill for me... however, 28mm is still wider than 21mm on APS-C so I'm good until 2017.
FTR, Pentax has a site for checking which lenses (FA and newer) are FF compatible:
P.S. Klaus, any chance of starting Pentax K FF tests?