I have Image 2B's, the precurser to the B25. I love these speakers. I've only been able to compare them to Titans from Paradigm, so not a fair contest. I have heard the Monitor 3's today, and I gotta say, I liked it alot. Very punchy speaker, more bass than the PSB I think, but it seemed a little, I don't know, off to me. That is because I listen to my speakers every day, and not a knock against the M3's in any way.
I've got a suggestion for you though. Listen to the Image 25Bs, and if you like them pick up the 2Bs on sale at soundcity.com for $239 a pair. I have heard both speakers, and there isn't much of a difference at all.