Yup, they're great. I've got an original Costa Mesa, so I''ve been tracking the project over the last two years to get the new version, too.
One correction: While the new uppers can be made to work on an old gun, the AR180B lower receiver is a completely different design internally that uses standard AR15 fire control parts. The new version also uses standard AR15/M16 magazines without modification (the original AR18/180 mags latch via a slot on the RIGHT side of the mag). Both are improvements -- but they aren't interchangable with the originals.