The E-600 is not the Roland top of the line. That title goes to the VA-7, although the G-1000 and E-2000 have some bragging rights in this area. However, I believe that the E-600 is probably a good keyboard and it is the one portable Roland with a vocal harmonizer.

As far as price goes, I would prefer a Yamaha PSR-740, which can be had for about $1000. So the E-600 is worth somewhat less. If you do not care about the vocal harmonizer, the E-600 is worth cosiderably less, more like a Yamaha PSR-640. However, many people like Roland styles and sounds better than Yamaha. The E-600 might be a great keyboard for you. But I do not see how it can be considered objectively as Roland's best keyboard.