I have a JL 12W6, and I really like it.. I have it connected to a mono 125W channel on my Xtant 403a. running at 3ohms. in a sealed box I purchased from a local audio shop (JL retailer)
it's 1.25 cubic feet.. with a little bit of fill it matches perfectly with my JL.

I also think a single 12 might be a better replacement for the dual 10's. you get a little bit lower in the frequency response, and the JL 12W6 in a sealed box won't loose much acuracy in comparison to the 10's