i am glad to see that you had the chance playing the e50 a little bit. as i was saying in another post, in about one month time i should get the e60 i ordered blindly (now many, including myself would say that is a stupid thing to do ) and i am soo anxious playing it!
while i was reading your post, i realize roland was clever introducing two keyboards that differ only on how many keys they have (61/76) but other than that almost identical, because this way they collect also the users that were/are not happy with psr3000.... see my point? and of course i was expecting (at least slightly) better sounds from e50.60 compared with psr3000 even only because is a newer instrument, if not a newer sound generation.....
now i am even more anxious for my new roland....
and consorning the use of guitar mode, i believe is a great tool for writing new styles, especially "live band" type, and not that much something you'd use while performing live.