Here's my situation. I am currently using Polk Monitor 70s for my front left and right and a Polk CS20 as my center. A friend of mine has a pair of Boston Acoustics RS334 for his left and right as well as the Boston Acoustics RS260 bookshelf speaker as a center. He hasn't used this setup in a while so it's in his basement storage just collecting dust. His wife wants to do some spring cleaning so he's offering to just give it to me. Is it worth it to switch from my current setup to his?
Well, I would go ahead and take them. Bring them home and set them up next to yours and see how they sound. If you like them, just replace yours with his and use your polks as surrounds. If you don't like them you could use them as surrounds or just offer to give them back or come up with some idea for them.