I doubt that most people haven't already compared voices already, but here's a comparison video that got put up a few days ago.
http://www.nicovideo.jp/watch/sm11435330For me, this is just gonna take a little getting used to. My first reaction hearing her sing Idolm@ster (without anything to compare it to, before this video was up) was, honestly, that something was off. I'm not saying it's bad, it's just different, and I'm gonna have to adjust to her new voice.
Speaking, though, I think that's gonna be easy to do. She sounds quite like the original Yukiho, with some small differences. Chalk it up to...
... growing up...