Wow! Many great responses, as I expected. I should have been a bit clearer in my original post: the headphone bleed occurs when I take one can off my ear, which I do about 50% of the time I'm tracking, depending on the style of music & vocal.
I'm pretty surprised to see cafehonda's response; evidently he kicks ALL vocalists out of his studio, at least the ones who know what they're doing. Haha. (I jest, I jest.) My voice is EXTREMELY dynamic, so I go from a soft near-whisper to belting loud enough to destroy ribbon mics within the same take; hence the need for fairly drastic mic technique. If I *didn't* do this, THEN I'd be creating a nightmare for the engineer.
So to clarify: I was interested in the bone-conduction tech because it allows the ears to remain open, which would provide the vocalist the ability to hear him/herself in the room/booth while simultaneously hearing the mix. Like I said above, I record vocals with one ear off about 50% of the time; the other 50% of the time I want to hear the sound of the mic & pre (and compressor, if there's one in the chain; with me, I track 95% of my vox through a API 512A into a EL-8 Distressor) and how they're reacting to my voice.
The main reason I want to eliminate any/all headphone bleed is due to how my vocals are processed/mixed when I'm working on my own material; there tends to be 2-3 compressors on my vocal during mixing and that really makes any bleed jump out and grab the effects on the vocal, which isn't pretty (in most cases).
Really appreciate all the responses, especially the funny ones. It's like Dave Chappelle said: musicians & comedians hang out a lot, because timing is important in both music & comedy...and musicians think they're funny. Hahaha.