The primary reason to use a center speaker is to keep the dialog centered on the screen for people that are sitting considerably off axis. If you only have a single sofa in front of your TV and you're sitting 10ft behind the plane of the speakers, the center channel really isn't going to add that much. In fact, it may even detract a bit since timbre matching between the Salons and Voice is not perfect (although it's one of the best available).
If you're sitting closer or have a wider seating arrangement, the center channel may be worth it.
I can see why you think your room may be too small for surrounds, particularly if you have your system set up along the long wall. If practical, you might consider moving the system to the short wall which may provide more room for the surrounds. The downside, of course, is that your main speakers will be closer to the sidewalls, and additional acoustic treatment may be required to reduce first-reflections from these walls. I'm with Sdcampbell in believing that surround effects are a bit over-rated. Still worth having if you've got the space and budget, but not as important as excellent front sound (which you've certainly got with the Salons).
If you're sitting closer or have a wider seating arrangement, the center channel may be worth it.
I can see why you think your room may be too small for surrounds, particularly if you have your system set up along the long wall. If practical, you might consider moving the system to the short wall which may provide more room for the surrounds. The downside, of course, is that your main speakers will be closer to the sidewalls, and additional acoustic treatment may be required to reduce first-reflections from these walls. I'm with Sdcampbell in believing that surround effects are a bit over-rated. Still worth having if you've got the space and budget, but not as important as excellent front sound (which you've certainly got with the Salons).