I use chalk with regular deadlifts and straps for heavy sets of SLDL. With the regular dead I don't think you should use straps as just quickly resetting your grip before each reps works well, and also going strapless helps strengthen the grip. Power lifters especailly shoildn't use straps on regular deads.
I cannot hand onto the bar if I go over 5 reps in the SLDL though unless I use straps because you cannot reset the grip between reps. I train my grip, and have a pretty decent grip I think, but I still need straps with SLDL.
Oh wait. I remember. On speed days I always wanted to DL. Because I LOVE it. But I couldn't do DLs and GMs on the same day, either, because of my screwy back.
(I'm going to spend some time going over my old training logs...)
We don't do them both for max effort. We may do one as a second move, but in a variation that uses different muscles than the first move. Did that make sense to anyone but me? lol