I would set them to small, since you've got a sub. That's what I've done, even though I've got large surrounds. The proof is in the listening. Try it both ways with material you know well, that spans full range, highs to lows.
I had the same sub! They were all I could afford for a surround system. Compared to nothing, they were awesome. But in absolute terms...my SVS are an upgrade :)
At $250, should you consider a sound bar? I've been doing a little reading for my dad, who needs a replacement for his HTIB. I'm starting to get drawn towards these sound bars, but I don't know enough to recommend them...