After additional testing (and screwing up rounds 1 of two credit tournies) I think Max putter is not any better than Rossa, possibly worse (the only good thing is better balance, for which reason one can nail more long putts)
The problem with Max is that although it has great many meter increments (10, 20, 30, 40) steps within each increment are few and bad (for 10 you have only 4 and 8, for 20 similarly). For this reason, if you don't notice this (as I didn't for a while), you can miss great many totally doable putts (I even missed a straight 6 footer, by aiming 6 ft which was short...) If you do notice it, you always need to calculate much and makes it hard to achieve stopping 1-2 ft behind the hole...
Rossa's biggest advantage is both great increments (15, 30, 60) AND many steps for each increment (I think 5 or 6). This may in fact be the secret why Rossa is so much liked, as information regarding steps is not available in the pro shop description - you can only find it in the forums or by trying.