Purpose of using same speakers for surround?

Interesting thoughts all, and perhaps my topic was a tad too broad?

I can now see a definite merit for same speakers if I were listening to classical music via MCH SACD... I am not. Clearly this would be ideal for those that do.

For me, I listen to various forms of music including rock, modern jazz, pop, and r&b among others, which I run through 2 channel via an AH! cd player.

I also like concert videos, and movies in 5.1, via DTV(HD), or a Panny Bluray.

My modest system includes a Rotel 1077, NAD T175, Mirage M7si - MC2 - PS10, and early Paradigm's for the rear.

I'm not talking about a major investment in picking up another set of M7sis, but for those of us with similar listening habits, do you feel the change would make a significant improvement, or not worth the effort?

IMO, for not making a major investment, I feel the change would be a significant improvement and worth the effort.

Purpose of using same speakers for surround? TIMBRE.

I just saw Mission Improbable at an Imax theater. While I couldn't tell exactly what speakers they were using for the rears they were very large PA looking. I don't go in much for today's shoot-em-ups but the previous MI's were at least somewhat believable, well subjectively anyway.

The sound track had some moments were the rears were at a very high volume with almost nothing coming from the front. Seldom used, the effect was very dynamic. Numbed by the shear excessive use of what's become one note explosion low frequency the audience was clearly startled by this massive discrete jolt from the rears.

Is this an indication that film audio is beginning to get over the ridiculous? Maybe not.

In my previous 5.1 system using "surround" speakers the effect was novel compared to my current 7.1 using matched speakers. As a reminder, 7.1 is not about room size. It works very well in a small room.

If your combining two channel and HT you need to bias the quality of one or the other. IMO two channel is simply too delicate. That said, matched speakers are worth it.

OK... so I'm using M7's up front. I can pick up another set of M7's for the rear. Per your recommendations, this solves my 5.1 dilemma, but there is no way I'd be adding a 3rd set for 7.1 LOL! It's a good size room, but not THAT big, and the wifey would probably pull the trigger if I tried having 6 of those towers in my bedroom!!! Guess I'll be with 5.1 for quite a while, but that's my mo anyway. The closest I ever get to new is new old stock :)
BTW, is there even 7.1 material out now?