Looking on the various Roland sites the E60 and E80 are as follow:

E60 has 512 mbit wave rom, it has over 1000 panel tones and 32 drum kits and over 120 styles

E80 has 1 gbit wave rom, it has over 1100 panel tones and 54 drum kits and over 350 styles

My local music shop tells me the sounds are the same in the E60 but not as many and also far less styles in there. The E80 probably utilises sounds for styles missing in the E60 so the extra styles this has will probably not be compatable with the E60 otherwise everyone would buy an E60 instead?
Question is are the extra 100 or so panel tones, 22 drum kits and 200+ styles in the E80 worth the extra money over the E60?
Reading the review that Abacus gave on the E80 on another thread you may all be better waiting to hear these for yourselves.