I had a RC-42II & it was OK, but, inadequate, so I sold it at a loss & bought a single Heresy II off eBay to go with my Heresy II Fronts & Surrounds.
The Heresy II is wonderful for my set-up; therefore, I recommend a Single kg4, or an Academy. I've seen a few single kg4 for sale, and many Academy on eBay this year.