Non-matching front L/R speakers in a 5.1 setup?

Hey guys... So I have a pretty mediocre HT setup- Polk TL rears and center, PSW10 sub, Polk Monitor 50 fronts, all run by an HK AVR 1700. I know, not great, but it’s what I’ve got. Anyway, I recently inherited Dad’s beautiful pair of ProAc Super Tablettes, and refurbished those babies. 

The ProAcs sound superb, but really do lack in low freq (as they should for their size, not a complaint just a fact). What I’m contemplating is using the ProAcs as my front L/R in the existing HT setup. This would a) provide some needed bass via the sub, and b) introduce some needed sound quality up front...

Whats the prognosis? Good idea? I’m reading a bit about “matching” the fronts with the center, and I’d certainly be mismatched as far as brand (although it doesn’t seem insanely mismatched physically). I’m not sure if my AVR has a ‘phantom’ center setting, but I believe there may be a way to make that happen. Basically, I’m looking for some input/advice/suggestions, you know. Maybe you’ve tried this, maybe you know a thing or two about the pros and cons....

Hope to hear more from you fellers! 

The ProAcs are a BIG step-up and will smoke the Polks...not even close.

So far so good for 2-channel....BUT ( and its a big "But"....) multi-channel (5.1/7.1) have their primary dialogue track purposely encoded in the Centre Channel . Its not one to be compromised

IMO do the right thing and go invest in a matched ProAc CC speaker ..... bottom line. IT DOES make a difference and is a strongly preferred.

The rears/surrounds are non-critical and artificial fill-in manufactured tracks in any case, so you can chintz it here and just stuff in non-matching speakers , no problem.

 Otherwise you are leaving yourself short, bigtime.

I generally recommend against mixing L/R and Center speakers from different manufacturers.  It doesn't mean that you can't do it.  What happens is that you will hear a noticeable change in sonic signature for HT movies as sounds pan from left to right.  An example would be a motorcycle driving across the screen.  The change in sound will be very apparent when the sound start on Left speaker and then pans through the Center and finally to the Right. 

Like akg_ca said, for HT, the center speaker is the absolutely most important speaker because 90% of the sound and dialogue comes from that speaker.  It depends on your priorities.

For surrounds, it is my opinion that they do not have to match exactly, but they should be somewhat close in signature.  I am running B&W front speakers with some older Focal surrounds and I don't have a problem.