We have used WDW passes at DL a few times. We sometimes buy 10 day no expire WDW hopper passes, to use on several trips to WDW. If a DL trip comes up, we have used them there, too. It depends, if I am going to DL for 4-5 days, I buy a DL pass. But if it is for 1-2 days, we have used the WDW passes.
It is a little delay at the turnstiles, when the go to call WDW to have them remove a day of use from the WDW pass, and give you a one day hopper. I could never understand why they do not have you go to guest relations, but I guess they want to make SURE you use it immediately, and not get the one day hopper and sell it or something.