Although timbre matching can be vital to creating an equal sound all around, many people have mixed brand systems and have found a good integration for music or home theatre.
Take sushi for example, who has Hales System Two up front, the
Axiom VP150 as centre, Axiom QS8 for surrounds and a Hsu VTF-3 for a subwoofer. He has found that his Hales sound very similar to the Axioms so perhaps the sonic differences mesh really well for his preferences.
Personally i like to keep my front 3 speakers of the same brand and model types (left, right and centre) but certainly you can mix and match brands depending on how they sound.
Once again about the best thing you can do is try them with your system because only your ears will really tell you if it sounds good or not.
