"Can anyone tell me how the M3's might differ from Polk speakers? Specifically the Polk RT series?"
I own Polk RTi8s (floorstanders) and M22s. I know this is not the exact comparison you are looking for but I think there are a couple general principles that apply. Both sets of speakers are excellent. Neither speaker is "bright" like Klipsch (my previous favorite speaker) - they are revealing. The M22s sound like slightly smaller versions of the RTi8s - which they should as they are bookshelf speakers. Both speakers have allowed me to hear instruments I didn't previously appreciate on CDs that I have had for many years - and heard on some relatively good speakers (Mirage and Klipsch) many times. I think both Axiom and Polk (at least at the top of the Polk line) make excellent speakers that sound very similar, but with Axiom you probably get at least 25% more for your money in terms of quality when you compare them to the Polk's retail prices.
If you think the Ascends offer more than that, go with them. But I can assure you, you won't be disappointed if you choose Axiom.
