There's all kinds of good speakers out there, but if the Polk RTs are the ones I heard at Circuit City a while back, the guys on the polk forum are smokin' crack.
The LSi 15s that I heard were very nice, but the RTs had boxy, muddled mids, decent bass and your typical un-offensive rolled off tweeter. At least that is how I remember them. Could have been the room, material, etc...
I had M60s in a 14x14 bedroom and they were positively fat and rich in that environment. Certainly more speaker than necessary, but they did sound good in there.
I think your taste in music and typical listening level should probably determine which speaker is best for you.
