I've never owned a non-Westy Vanagon, but the littl (if any) noise from
a properley fitting pop-top is way overshadowed by the noise (read that
'inside a base drum') from the rest of the vans panels.  Adding sound
deadning to the doors, hatch, and side panels can make a BIG
difference.  Wind noise from the top is the least of your sound
worries.  And the big advantage, other than being able to stand up to
get things done, is the additional bed above (wider than below on the
camper) or use that area for storage while in camp, a great way to store
clothing, food, etc so that it is handy while in camp.  It makes a big
difference in convenience if you are stocked for a week or two of
'boondocking'.