As tables have 8-9 players all the time (except when the field shrinks down to the few final ones), the abb-to-bb ratio is more or less constant, assuming that the ante is a more or less constant fraction of the big blind. (Generally, abb = bb + 6*ante at a full table. E.g. if the ante is 1/10-th of the bb, then abb = 1.6*bb.) Thus people prefer to talk in terms of bb's, but they might as well talk in terms of abb's, that would change only the absolute numbers but not the pot odds or guidelines.
Well, it does matter a bit because you might get short in an early stage when there are no antes, so I still advise to use abb for the sake of unification. The main thing that matters is the (preflop) stack-to-pot ratio - the ratio of your stack size to the size of the pot (that you're going to steal). MTT players have been calling it the M number since Harrington's times, and that's the lingo used in Pokerstrategy's articles as a homage to the tradition. Under the new terminology, the stack size in abb is, by definition, exactly 1.5 times the M number.
At which stack depth to start playing push/fold is a separate question. Coincidentally, I raised this question at tonight's Russian coaching, and the coach PuBePaHeT (pronounced as 'rivera net' = 'there's no river') advised to minraise (and fold even 4-4 in MP to a 3bet-shove) instead of openshoving even with 10 bb ~ 6 abb, but that's because he thinks most MTT regs are uncomfortable playing postflop and don't flat-call nearly as wide as they should (which is hugely exploitable) and also don't 3bet wide either (i.e. we usually have an easy fold to the 3bet except when we have premiums).
I.e. I guess the unexploitable strategy would be to minraise a polarised range (r/c premium hands, r/f weak suited Kx (as a blocker bluff) and low suited connectors that both can stand their ground postflop) and shove low pocket pairs + low Ax + broadways with 15 bb ~ 9 abb (you can use HoldemResources Calculator to examine the Nash equilibrium strategy for minraising and openshoving combined), but as the field is overly tight, people argue that minraising the entire opening range works better as an adjustment.
There's however no doubt that you should steal frequently in one of these ways. The antes surely make the risk-reward ratio of stealing much better.
