I have the VS-1680, and included two effects boards when I bought it a couple of years ago. I've been very happy with what they provide, and although I haven't used all of the effects (there are many) those I've used have been impressive and have been quite adequate for my needs (esp. the COSM speaker modelling - I already had the DS-90s).
I think I paid around $700 for the pair of boards - I might have got away with just buying one - but when I think of how much external processing $700 would have bought (nearly two years ago), I would have to say that they were pretty good value for money. Also, having them "built-in" eliminates the wiring and cabling which can be a nightmare in itself.
Hope this helps -
- Wil
