Roland G 70 has 192 Mbytes
Roland E80 has 1024Mbits:8= 128Mbytes
Roland E50/60 have 512 Mbits:8=64 Mbytes.
It is better never to use Mbits as this may confuse readers.(In the latest list of specifications Roland does not use this anymore)
Difference between E80 and E50/60:
E 80 has more powerful sounds and they have a higher definition.
New drumsamples are stereosamples, but in E50/60 they are mono.
All sounds are compatible, which is very useful for styles and smf.

Keybed: The keybed of the E60 is different from E50.For me they play much better.They are also 8 millimeters longer.