Unless you find a great deal because it's a 'combo' deal, I wouldn't get a pre-wired one. It sounds like you have some relatively complicated (nothing you couldn't handle with the help of some drawings and forum members) wiring needs, and you'll get more flexibility doing it yourself.
You have all kinds of options-- if you're already happy with your two single-coils, I don't see the need to replace them 'just because' you already have your guitar apart. Put your money into a humbucker that meets your needs.
Recommending a pickup is like recommending a car-- since each has its distinct personality, it's hard to recommend them, and besides that we each have our own experiences and biases.
That said... why not just get a classic PAF-style? Sure, it's not an overdrive monster, but it'll produce more output than the single-coil you're already using, but will be more useful for clean applications. Most companies makes a 'classic PAF' humbucker, so just get one with 4 wires rather than the equally classic 'braid', and you'll be able to do coil-splitting if that's what you want.
As for the coil split... a single coil from a humbucker won't really replace a true single-coil pickup sound, but since it's the 'in-between' sound you like anyhow, you should be able to get a fair approximation. I would add a push-pull pot to split your humbucker, which will require the least amount of modification and no cosmetic changes.
If I can dig it up, I can also post the coil-split modification I've done on my tele (with a Little 59), which doesn't even require you to swap into a new pot. It's a fairly elegant solution, but has its drawbacks-- it's a humbucker with tone control up until about '8/9' on the tone knob, and then when you hit '9/10' (I say 9 because it occurs before you're at the very end) the coil is split. That means your tone control isn't useful in single-coil mode, and a bit of the range is taken out of the humbucker, but it's a pretty nifty mod.
Cheers,
Greg