The major contributors to "waste" when flooring it, that I know of, are (in no particular order):
1. Engine friction,
2. Rich mixture,
3. Torque converter losses,
4. Drivetrain friction.
Torque converter losses eventually go up with applied torque, even though they may be "funky" at lower torques. Engine friction is an issue at high RPMs, but you get better efficiency at high RPMs as well, so it really depends on a particular engine. Rich mixture is a factor as well, especially if you're not using premium gasoline. Drivetrain friction on gear pairs simply goes up with torque, so if everything else were constant, you'd want to minimize the torque, but of course everything else is quite complex so this has an effect, except when it doesn't ;)
What I've noticed is that using regular gas I get worse mileage with jackrabbit starts, compared to premium gas. It's easy for me to test, since 99% of my driving is on the same road every workday. We do groceries and errands in my wife's car. For freeway driving that I do very occasionally, and is mostly on cruise control, there's no benefit to premium gasoline, other than slightly quieter engine operation (the difference is measurable, but is really meh otherwise). In my city driving, it's actually cheaper for me to use premium gas.
So, if you're using regular gasoline, you probably shouldn't be flooring it, but on my particular car there seems to be no big difference in gas consumption between aggressive starts and less-aggressive ones if I use premium gas. The biggest impact to me, it seems, is from slight "hypermiling" - letting off the accelerator way ahead of stopped traffic, coasting longer. When I do that, jackrabbit starts on premium gas seem not to matter at all.