I preferred the Philharmonic AA's over the 340's, but, as said it is user preference. I appreciate that Dave got generally great performance out of the drivers he used with nothing really "wrong". I felt the AA's were a bit more neutral, but the 340's were still quite good.
The 340 and 170 have very much the same sound, but the 340 are decidedly more powerful speakers (and impressed me as more powerful than the AA's - though I didn't push either that far). Depending on your room size, you could save some money with the 170's, or shipping would be less if you evaluate the 170's. If you like them, they could be your surrounds and you could get 340's for the mains if you decided to go Ascend.