Sherlock/John/Lestrade is my OT3, and I say that very seriously and unironically. Lestrade really balances both of them out sometimes; Sherlock/Lestrade would never work without John as the bridge between them, John/Lestrade would always be diverting part of their attention the Sherlock, and while I totally see Sherlock/John without a direct involvement of Lestrade (obviously, lol, wouldn't be writing a 100K+ fic about them if I didn't) I think that including him both delivers the excess of stimulation that I can imagine Sherlock might need and a bit of a breathing point and emotional support for John at times, when Sherlock is being all crazy and non-human and pricky.

So, haha, yeah. I ship it. :p