PMC or M&K for Home Theatre

I currently have PMC speakers; two AB1 in the front (l&r), a center LB1, and two LB1 in the rear (l&r)

I am running an ATI 1505 5-channel amp with a B&K reference 10 pre amp.

Now my question.

The system was originally purchased primarily for audio listening with some home theatre (that's the reason why I went for the larger, more expensive AB1s in the front). Now, I find 90% of the system use is for home theatre.

So, I've been thinking about changing my system (pre-amp for sure, and possibly speakers)

I recently heard an impressive and reasonably priced M&K 750 THX Select system (not the package system) with 5 - 750's (not the 550s in the rear)and the 1250 sub. It sounded outstanding for home theatre.

So, here area my questions:

- Is it true that for accurate home theatre, all 5 speakers must match? My current PMCs are amazing speakers; but don't seem as efficient for home theatre as the M&K - although they are much more expensive speakers - does the size/model mis-match have anything to do with this?

- Is anyone familiar enough with both of these speaker systems to comment on whether switching to the less expensive M&K would be a mistake? I know both manufacturers claim to be used for studio mastering...but while I realize speaker preference is subjective, I'm very curious as to informed opinions on the two set-ups.

Many thanks!
I have not heard these particular M&Ks. OTOH, there's no need for 5 identical speakers for HT, although I would make a case for them for multichannel music listening. That said, unless the PMC's are too big or lacking is SAF, I would stick with them. (Or send them to me. ;-0)
One of my brothers purchased the M&K 750 thx system with the 1250 sub and he absolutely loves it. He turned a two and a half car garage into a play room with a HDTV - he's using the Sherwood am9080 and matching processor and it absolutely shakes the room. I've heard great things about the PMC although I've never heard them - all I know is that when my other brother installs his home theater he is going with the same M&K system.