I use 1 watch when I travel. My white dialed Explorer II. I love the fact that I can keep track of Hawaii time vs where I'm at. (Japan, Canada, Paris, NYC) It allows me to call home and not call them at 3am accidently. :-)
I dont think it really hinders the ability to adjust to the timezone difference. For instance it was 12 hours difference while we were in Paris a week ago. After the 2nd day I was on Paris time, I think the fact that the sun went down at 10PM everynight was more confusing than having the watch tell me the time was 10am in Hawaii.
In fact I love the watch's GMT feature so much I'm strongly considering it to be my 1st genuine purchase, more so than a Submariner.