I am both a Roland and Yamaha Arranger dealer. The Roland E80 has not been a big seller here in my store. First, many people have a very negative opinion of Roland's direction in arranger keyboards throughout the USA right now. Roland made a decision last year to combine the pro and piano/arranger division. Many of the readers here have seen the main problem.........Roland can't find dealers that want to sell the high end arrangers for a number of reasons.
Of course Yamaha has dozens of arrangers in their line and so they are more dealers selling these keyboards. They have all price ranges covered and as many here have seen, even have support available from Yamaha US right here at the synthzone forum.
Steve Deming has been monitoring this site for years now.
As to which is better I would say that if you need more up to date features and some of the newest and most impressive sounds (articulation 2) you might be better served getting the Tyros3.
You get a hard drive and USB flash drive capability compared to the E80 only having an external compact flash card for storage. The Yamaha also has a built in audio hard disk record feature which allows you to record vocals and instruments along with midi files, styles or songs you've recorded in the Tyros3.
I won't get into the user interface on each because they are both very good.
Some will say the Roland piano beats the Yamaha and vice versa, but both are really good in the sounds.
I hope this helps,
Kaye's Music Scene