Adam, I'd pick the L&R speakers that work for you 1st including type (i.e. in wall, on wall, in-on walls or full bookshelf). Then for your center you keep with the same type, but you now have a choice of vertical or horizontal. If you go vertical, ideally you get the same as your L&R so you have 3 identical speakers across the front. If a vertical center is not for you (does not matter the reason), then choose between the 100 and 150. Differences in matching are quite subtle, so you'll be fine with whatever you choose.
For instance I had the VP150 which matched perfectly well with my M22's, but when i compared it back to back with the M2, i found the M2 matched my M22's even better than the VP, so I made the switch. That's the short version of the story anyway.
Nothing will be a loss, just slightly different shades of performance and value, all you have to do is pick what works best for you regardless of any opinions we share. Have fun with it!
