Shoutbox

I had a K700i and it took forever to xfer any music across to it.  Aside from that, it only has about 40MB internal memory with no external memory support.

These two reasons alone (aside from the upgrade being free) are why I upgraded to a K750i.  External memory support (and I get 30% discount from work on the cards) & it takes on average about 90 seconds to xfer a music file across (depending on size, of course).