I'd say pluses for the Yamaha's... Mega voices (at this price point you can't use the SA ones) and better styles (but only some genres. Roland's modern beats are much better, IMO).

Pluses for the Roland... The drums, without a doubt. Almost ALL the sounds in the main drumkits (several kits worth of them) are multi-velocity, and if you get the GW-8L (no news yet on whether the Prelude will have a GW-8L clone version), a set or two of multi-velocity latin percussion to die for. Much better pianos (unless you LIKE that brittle thin Yamaha sound!), E.Pianos, etc..

So, all in all, it's pretty much the same old, same old when it comes to Yammie vs. Roland. Are the style guitars more important than the drums and bass? Do you want punchy and warm, at the sacrifice of style selection? Do you LIKE cold thin pianos?

I don't think the battle lines have moved much with this model...