Polk Audio RM6880 upgrade advice

I saw that I could get Polk Audio TL3 speakers for around ~$200 (oops, plus shipping). Was thinking of seeing if that would be a good cheap upgrade from current setup. Living in an apartment so I'd keep the side-firing subwoofer from the RM6880, but basically looking for better sound (girlfriend still needs closed captioning). Would likely pass along the existing RM6880's to someone else or hold on to them maybe.

Does anyone have experience with these setups? Here is my current:

Polk RM 6880 - 7.1 (bought 2 additional sattelites a while back)

Denon AVR-1700H

Thank you all in advance for your help.