I have a full set of polks from the 90's I think... got them off craigslist a few years ago. rt##i series. It included a not so stellar center speaker. Then I found a CS400i that had the same drivers as the front speakers (rt35i's) and couldn't be happier. It's a pretty big center, but I doubt I'd ever go to a sub-6" driver center again, regardless of the name on it. I have an CSiA4 in storage that I don't even use. Was just too thin sounding.
Being in an apartment, having a boomy sub running all the time is somewhat inconsiderate, and having small drivers in the center just doesn't give the depth/richness I really look for when watching movies. It's a shame a lot of what you find these days are small centers, so much of your movie audio comes out of that speaker that you really need a decent range speaker in that spot.