As it can be seen (again) in my benchmark results, at
http://stlavlmap.sourceforge.net, the AVL tree is faster for some
operations, but never slower for the rest.
The test codes are very simplistic, and I won't claim they give
conclusive results. So I'm sending this e-mail to:
1) ask if anyone is interested in testing it; my system has too little
memory to create bigger trees, so my measurements may have too much
noise.
2) suggest it to be integrated into libstdc++, if the tests on other
environments confirm my measurements.