1 pointThere is a section in Ch 13 called "Front End Duties" that talks about how the front end still contributes, and also addresses getting on the gas too early. Notice that when it says in TOTWII that the bike will maintain its lean angle even with the front wheel off the ground, it does NOT say that you have maximum corner speed/traction in that situation (you don't), and the section referenced above on front end duties talks about that. While you do see racers commonly wheelie out of corners, you don't see them wheelie in the middle of the corner at max lean angle, because you just can't load the rear that much at max speed and lean, it would lose traction before it would wheelie. Another thing to note is that while acceleration alone can and does cause wheelies, another thing that can contribute is the release (rebound) of the front suspension as the bike is coming out of the corner, and that may be some of what you are seeing in racing. Some riders - not going to name any names here - when launching a big show-off wheelie, use a sharp suspension compression/rebound to help loft the front.
1 pointRemember that the 60% is not exact, the ideal weight distribution depends on the bike and also the tyres. I don't know the answer for sure, but logic suggests that if the front wheel is not lifting all the power is going into forward motion (minus power train losses, and anything wasted by rear suspension movement). So even if the front is off the ground, but is not lifting or dropping, all the power is going into forward motion. My observations while at the track seem to support this - an RSV4 had overtaken me before the chicane going onto the start/finish straight and just after that chicane is a crest which most bikes will wheelie over. I had tucked in behind the RSV4 on my 1098 and he wheelied while I didn't, which allowed me to pull alongside. Not sure whether this was rider skill or wheelie control but the front wheel of the RSV4 then hovered at a consistent height and the RSV4 was able to pull away. Of course it has a lot more power than my 1098 anyway so that's a factor too (he may have been wasting power and still have enough to pull away). But that particular rider is a nutcase so there's that factor too
1 pointThis is pure speculation but I'd imagine that the front wheel begins to lift at a point well above 60% weight distribution. But if you could instead find a balance point where all of the power being used it for propulsion than lifting the front wheel, where would that be in relation to the ideal 60%?