ian, of course all the comments are helpful! especially yours!
but still, they are simply not relevant. they can not be. they are too subjective.
telmo, do your homework and check for yourself all available materials (webs, manuals, demos, forums) and of course both keyboards if possbile!
Yamaha S770, Studio One 3, EMU 0404USB, ESI, ATH, Dell. And others.