I love my RTi 12's. Hopefully someone else who has the av123's will write up their thoughts on them for you.
First off the 12's will perform almost exactly to the specs that Polk published for them. The freq. response is very linear. I have never been able to hear the points that the crossovers split the signal between the three driver sizes. The highs are quite good, never harsh or bright, typical of silk dome tweeters. The mids cut through with clarity bringing voices and lead musicians to center stage, right where they belong. The bass side of the 12's has a great deal of potential, but you are going to need serious power to flesh the bass out. The bass drivers are in a huge enclosure, read 3/4 of the entire cabinet, helping them to extend deep into the lows. Polk recomends 50-500 watts af amp. With a 90 db sensitivity theese babies will scream if asked to.
I have been using my 12's with my denon AVR 4806 and have been very happy with the sound. So far as amps go my 140 wpc receiver has been able to drive them. to be pointed out however, the denon puts out around 183 wpc in stereo, so your milage may vary. I also have tried running the 12's full range and then crossing them over to a sub at 80 hz. The latter results in a better bass response in my room.
When listening to music the polks dissapear into the background. leaving the music to take the stage. When listening seated in the "sweet spot" the imaging is simply stunning. However, move left or right of the sweet spot and the imaging loses focus. Fun story here, I had a former acoustical engineer for boston acoustics over for movie night. Before the movie I was showing off My setup playing Santana Abraxis SACD. This album is recorded in stereo. While playing this I actually had to unplug my center channel speaker to convince my guest that I wasn't using multi channel playback! That speaks volumes on the imaging.
The main thing is to listen to them and then make your decision. At $100 you can give them a listen and have them there for some A/B comparisons. Then if you don't like them P.M. me and I'll Buy 'em.
Hopefully someone will step in with a review of the av123's for you. I know Mike c, I kinda did exactly what you said. But I thought I'd share anyway.

Have fun, new gear always ROCKS!!