Subwoofer selection here in the states is pretty awesome, but just keep in mind a subwoofer doesn't need to match the speakers (unless they have some aesthetics you want to match). B&W subs here are expensive for their performance in any case. JBL consumer subs have had a reputation for amp issues over the last several years but can be a decent value; never been impressed by Polk subs' performance altho that seems to be one of their better efforts. You may still need two subs for your room volume (don't remember how big your room was) and also for smoother frequency response across more seats.
The B&W CM series speakers gets generally good reports, but tend to be pricey, I've not heard them. The JBLs Studios are similar to what I've got, but a step down, and generally get very good reports, I find them quite good for the money. The Polk LSi series gets generally good reports but haven't heard them myself. You might search this forum and perhaps avsforum.com for user comments on all these series.
Good setup would definitely help any audition, particularly subs. Were you able to A/B/C compare or? Might even start a separate thread just on the pros/cons of these three sets. Did they seem an improvement over the current Polk setup you have?