It turns out my mains are actually Klipsch RB-51's, not 41's like I posted. I remember considering both when I bought them and I think because my center channel is the Klipsch RC-41 II, I was thinking they were all 4". Boy, do I feel stupid. At least that turns out to be good news and, while I can't find a FR graph for them, they must go a fair bit lower than the 41's (Klipsch says down to 50Hz). So that should alleviate my concerns.
I guess I am going to go with two of the VH15's then. I also just noticed that Power Sound Audio is located about 15 minutes away from me. Maybe they will give some kind of discount if I pick them up instead of them shipping them.
Anyway, I now need to read up on how to set them up properly. If you have any good links regarding set up, please post them. I'd appreciate it.
Thanks everyone for all your help and advice.