Regarding casting SW:D as a priority over DP above 25% and during movement:
Given that during any movement you're going to want to stagger your DP casts as DP, SW:D, DP, PW:S, DP, *out of instants =/* to avoid the "A more powerful spell is already active" nonsense, you'll almost always cast SW:D anyways unless you are moving for less than a gcd. I still wouldn't prioritize SW:D over DP for movement above 25% even if it turns out that it does better damage for the exact same reason that the Fury Warr rotation is focused around Bloodthirst and not Raging Blow: making a long cd ability the lynchpin of your rotation will cause problems. As long as you move far enough that you will need two instants to fill you casts, it will always be a DP and SW:D in some order. Since you will not cast SW:D above 25%, getting SW:D on cd early does not increase dps. However, move for more than 2 globals and you will be forced to use PW:S as your third cast if you had casted SW:D first, whereas you will get another DP in if you casted DP first. You will still only get 1 SW:D in unless you are moving for more than 10 seconds (god forbid), so casting SW:D first nets you nothing in the long run and comes at the cost of exhausting your instants prematurely and reducing the number of DP's you will be able to cast.
If you only need to move for <1 gcd and SW:D turns out to be a more powerful ability, go for it, but be sure there's no dps buff running out that would make refreshing DP a more attractive option.