This video shows a bass guitar where the neck projects all the way to the bottom of the body. Are there any production non-bass electric guitars where the neck projects all the way to the bottom of the body?
Contrary to intuition, R.M. Mottola put together a very good and reputable study on the effect on sustain of different styles of neck joint in last fall's American Lutherie magazine. Though none of the testers ears could actually hear a difference, the results of sustain consistently showed greatest sustain with bolt on necks, then glue joint, with neck-throughs coming in last. Argument has traditionally been the opposite. I've since heard many different theories as to why, such as the split and hardware effectively interrupting bar vibrations of the neck system, and a few others, but I've not heard anyone try to dispute the results. Then again, I haven't heard what great wisdom Ed Roman has to shed light on the study yet.
Really though, I think superior isn't an adjective that could really be used here. There may be some slight differences, but the neck joint is more often given credit for tonal differences only by correlation. A neck through Carvin, a mortise and tenon Gibson, and a bolt on Fender, have a few other slight differences in materials and design, and people often tend to credit things like the neck joint with more influence than I think it deserves. It certainly is one factor, but aside from this one study on sustain I haven't seen many attempts to isolate and quantify or even qualify exactly what it's influence is.