i used it for a while. i had some luck with it but hit some pretty severe downswings. that's when i moved on to hi/lo . you can expect some pretty severe fluctuation with the ace/ten front count.
the advantage for the ace/ten front count if you do it correctly (which requires a lot of wonging) ends up being around 0.25% if i recall correctly.
i think that figure was for a six deck game. sorry can't remmember exactly. but Blackjack Bluebook II has the proper procedures and specifics.