The Sterling SUBs are very nice--I'm hooked on mine. In the store, I didn't see or hear a big difference between it and basses costing twice as much. That said, they're not hard to come by, and the CV seems to be, so that alone might tip the scales.
Also, it sounds like the CV is good to go out of the box, while the Sterling really benefits from the volume mod. (If you go from flat or cut settings to treble and/or bass boost, the signal gets louder, so it's nice to be able to even out levels on the bass, rather than reaching for the amp. The stock volume can't really do this.) I'll also say that if you prefer a warm/organic passive sound, that's not the built-in sound of the stock Sterling (although it is achievable with a couple of mods).
In theory, I also prefer passive basses to active, but I really like the Ray. It's truly designed to be active, as opposed to some other inexpensive basses that seem to have preamps installed as an afterthought (or to artificially 'improve' the sound).
A few inexpensive mods got my Ray4 even more to my liking: I put a GFS alnico pickup in it (with a series/parallel switch) and did the volume mod, and it sounds a lot more more organic.
In my case, it seems like the legendary Ray4 hot output came from the pickup, not the preamp. (Unboosted, the preamp level is the same as passive, and distortion was never an issue--output was hot but clean). I put the original ceramic pickup in a cigarbox-type build, and it sounds excellent wired passive and placed close to the neck. (That pickup passive is hotter than my modded Ray4!) I didn't get to A-B the two pickups with the preamp, so I'm not sure quite how much to attribute to the new pickup and how much to the volume mod, but the preamp sounds better now--smoother, warmer, and generally more useful at a variety settings (the treble boost in particular is much more usable).
As for strings, I'm using GHS Pressurewounds--they sort of split the difference between flats and rounds, and they feel great.
