CMX 110 *is* on the existing "approved" list for ATT Broadband:
ATT approved cable modems
Theoretically, all DOCSIS cable modems ought to be there.
Sure is nice when the model is there, in plain print.
Don't know the pluses and minuses of this particular model.
PS: If you get $10 to $15 reduction in the monthly fee, these sort of cable modem deals are a no brainer - less than 1 year to break even. All "profit" (savings) after that. No point in renting for, in my case, 34 months @ $10 and paying MediaOne / ATTBI $340, 'til I switched! ;(
In any case, summer and thunderstorms are coming. They do, every year (heh heh).
Be sure to protect from lightning - once you buy it you own it.
If it gets fried, it's your problem and your bucks.