A max deadlift attempt, for me, doesn't really affect my form much, if at all. Last Tuesday, when I hit a new PR, I stalled mid-lift and I could feel my back starting to round a little (or start to give in, I'm not sure) - and it did - but I continued and completed the lift. My back didn't hurt at all, or anything like that, so maybe it wasn't so bad.
Anyway, I can't really give any advice other than: if your form is seriously suffering then don't continue with it. If my form was really bad from the start, that's probably the one time I would bail out of the lift personally. Of course, if you feel pain, abort.
Your form will be slightly compromised on max lift attempts, but it should still be good enough as to not cause injury.