There are tons of stuff you can do with 4 wire buckers... like you said. I myself just recently did a wire job for a friend that wanted a super hot rodded LP... I installed 2- 4 wire bareknuckle warpig humbuckers... He likes his tone nice and trebly... He's a lead guitarist for a local band... So I split the bridge bucker and wired it to a push/pull pot... the pot also controls the bridge bucker volume along with a pot for the volume control... I wired the neck bucker straight through with it's own tone controls and volume as well... I eliminated the 3 way switch and added an on/off/on for the Bridge bucker. I also added a killswitch... I'm not a huge fan of the set-up but for him and the music that he plays it's perfect... It gets great metal solo to blues to vintage tones... Not my cup of tea though... The Warpigs are hardcore output buckers too... so they're pretty mean.
Like you said though... there is a tone of different things you can do with 4 wire buckers... But, it all usually starts with splitting the coils.
