For me, it's simple. I can't play full (or at least, close to full!) piano parts on a 61. I can on a 76. If you are playing with a full live band (or ever need to), that pretty much dictates the 76.

Yes, the extra SRX slot is great on the E80, and the extra MFX insert effect for the Style or Song Parts (but you can do the same and better on the G70 with a workaround), and separate Mastering EQ and comp for Style and Keyboard Parts is handy too...

But none of them beat the extra SPACE to layout the sounds you want on a 76, IMO. 61 just forces your hand when deciding splits a lot more than a 76.

If Roland had ever turned the E80 into the G80 by adding the 76, it would be a no brainer for me, but sadly, what you get EXTRA in the E80 doesn't make up for what you lose. 15 more notes makes all the difference for me.

But if you NEVER play full piano, or Rhodes, don't split up the keyboard into three zones much or ever feel cramped on a 61, I'd go with the E80...

BTW, don't forget, if what you play requires separate outputs for different Parts (say you want to split the bass off to a bass amp or organs to a Leslie), or you want to use the VH and want a separate output for that, only the G70 has independent outputs. Four for the arranger, and a separate stereo output for the VH.