Hi Lo TC +3 on one deck resolution equals to Zen TC+6 on one deck resolution. To normalize among AP using different counting systems, level 2 counting system should use half deck resolution, so indexes, TC are roughly the same. For example, Hi Lo TC +3 on one deck resolution will equal to Zen TC +3 on half-deck resolution. Assuming from a Hi-Lo counter, RC=+6, there are 2 decks left, so TC = +6/2 = +3. At the same point, Zen counter should have RC close to +12 (since face cards, 4, 5, 6 have different tag -2 or +2 instead of -1 or +1). So 2 deck equals to 4 half-deck, TC=+12/4=+3. Both counters come to the same +3 TC.
You can ask for a survey, but the answers are, more or less, meaningless. Mathematically, the correct Hi-Lo TC at which to make your max bet depends on myriad factors: number of decks, rules, penetration, spread, and whether play-all or back-counting. The chapter 10 charts of BJA3 have the bet ramps for hundreds of different scenarios. Each shows at which TC it is correct to place the max bet for that specific game. You can also obtain the same answers from Norm's CVCX, which, in fact, stands for Casino Verite Chapter Ten.