How important for surrounds to match fronts?

Having everything match is not a bad thing and might provide a sense of comfort and insurance, but nothing wrong with mixing and matching as well as long as one is up to it and has confidence in their ability to do better.

I am a low budget home theater guy and simy run a 4.1 setup with my Focal mains and some "junk" rear channel speakers. I have obviously heard much better systems, but I don't feel like I am missing anything. I would have a matched center channel, but simply didn't have the room in the cabinet and have been happy with the ghost center effect.

With stereo audio the music is all you have, but with movies there is a significant visual distraction making the audio a smaller part of the overall experience. Great movies can suck you in no matter the speakers or TV just like great music can suck you in on any system, but I think movies can suck you in easier.

I can get a pair of aerial model 5s but i have no room behind the listening area

I concur with the other comments about the surrounds not necessarily needing to match, but have you considered finding brackets or shelves to mount the Ariel 5s on the wall? Just a thought....not sure you can do so however.....

I'd mount the Aerial 5s on the wall to the side of your listening position. In my experience it is important for the mid and HF to be similar to the LR mains, especially for music recorded in DTS.

After some experimenting, I use a pair of KEF Reference 102s mounted on the wall as surrounds for my Reference 107/2 mains. It adds a nice depth to the sound stage with DTS and many SACDs. The newer KEFs with Uni-Q just didn't sound right. I no longer use a center channel, and rarely turn on the amp for the rear channels, so I mostly use 4.1, or is it 4.2 with 2 subs.

db

I have done it both ways, and having all the same brand and family of models designed to work together a big difference in sound. I find on both 5.1 Audio (SACD/DVD-A) and movies especially noticable on DTS soundtracks. As mentioned is it a must have? No! But is it an avenue to maximizing the sound track reproduction, in my opinion and experience, Yes! Especially on movies where the sound shifts from front to rear or visa-versa, matching speaker voice creates a seamless transition. My advice is, if you can afford it, do it. If budget doesn't permit then try to voice match as closely as possible.