I've actually got the yamaha speakers in question and I've had about a year and a half of mixing on them. Yamaha is fantastic to deal with over the phone concerning parts and warrenty as well. The tweeter went out of mine and it was simply a phone call and 2 weeks later I was rocking again. (The tweeter was completely my fault... Don't ask.)
I find the speakers to be fairly accurate, but really, really 'dry' sounding. The bass end of things is tight. For the money I don't know how you could beat 'em. I'm really happy with them although right around the 5-8khz range it starts to sound thin and a bit artificial (I may not be saying that properly), kind of like you can hear where the woofer stops and the tweeter begins. I find my ears start to suffer from fatigue in about 3 hours, but that's not saying much because at 85 dB SPL my ears are actually distorting so my hearing isn't in the best of shape.
Anyway, good luck. At least you can be confident of excellent corporate support.
Andy