The sense I got from going through those posts and others were that the differences between the Polk's and the Axioms were in the areas where you were unhappy with the Polks, ie clarity of midrange and "presence".
I don't think you are going to find many people on here who will really criticize the RTi's -- they're pretty decent speakers -- other than to say that the folks here who have heard Polks are here because they preferred the Axiom sound.
I found a couple of frequency response charts of the RTi4 -- Stereophile seems to have one of the best -- and the charts do seem to indicate that the bass and high treble are bumped up 4-5 dB relative to the midrange, so the M22s would definitely be more clear in the midrange since they are ruler flat by comparison (well, a slightly bumpy ruler
All I can say without hearing RTi4's myself is that you will *probably* find the M22s have the sound you are looking for -- they get comments like "exquisitely clear midrange" in the reviews -- but it's hard to say for 100% sure.
At the end of it all, the best you can do is take a good guess and try what you think you will like in your own room. There are lots of people around North America who will be happy to have you over for an audition -- wouldn't hurt to give that a try if you live in a reasonably built up area.
[EDIT] Hey, look what Google coughed up. Randy (sirquack) did a search going further back and seemed to find some better posts :http://www.axiomaudio.com/boards/showfla...;o=0&fpart=
The gist of it seems to be that the M22s beat the Polk RTi's, but both people seemed to prefer the Polk LSi's over the M22s. What I took away from this was that LSi 9's at blowout sale prices are an awfully good deal.
It's interesting -- seems like if you read enough reviews you won't feel good about ANY speaker model