(1) If the higher end options (i.e. those with the "better than StrongARM" performance) really are the processors they say they are, battery life will be abysmal. I was more impressed than I expected by the performance of MicroDigital's Alpha Pro as compared with a StrongARM Risc PC, but the speed tests we did were accompanied by mains power to the laptop of course.
(2) Chris mentions market penetration of RISC OS 4 and RISC OS 5. However, another interesting comparison might be RISC OS Select subscribers as against Iyonix owners. Given the functionality still lacking on RISC OS 4.02, it's starting to look rather dated compared with RISC OS 5. How many Windows users (as opposed to RISC OS enthusiasts) will splash out for VARPC-SE (not cheap in itself) *and* Select?