I don't think you will find a common language that will fit everyone's needs and preferences. And for me, that's all right.
For my purposes, a unit will always be my normal min bet. If you want to know how many max bets I am ahead, I could tell you that, too, although like kewljason said, it sometimes varies what my max bet is. Also, sometimes I may play a $25 min table, and another time I may play a $50 table or a $15 table. So if one plays multiple table mins, I don't see how max bets helps either, especially if they are figured on a multiple of one's minimum bet, as mine are. To me units that are set at one's minimum bet level tells more about how well one is doing in terms of efficiency, even though the dollars may vary wildly between $10, $25 and $50 dollar tables. In terms of how well I'm doing overall, total net dollars is what I personally look to, not max bets or number of units. But that's just me.