I don't know that the sound difference between an ATV and UTV are really going to effect much. I have an 02 Rancher, it's as loud as most fourwheelers out there. I'll be more concerned with a comfortable ride with the next wheeler I get. I would like to have Independent suspension.
Recently I've been using my grandfather-in-laws new Honda Pioneer 1000. It's Way more comfortable then a 4wheeler, but not near as maneuverable once you get off of a trail. I haven't noticed much of a sound difference.
See I don't either but when I've mentioned it to people they've said "yeah if you want to scare off every deer in the county" like they have straight pipes on them. A comfortable ride is what I'm concerned with too. Those hills in north Jackson will beat you to death and you can't keep anything strapped on the racks.