I had my buggy at 81" wide and then went down to 78" and I really liked it at 78". 3" doesn't seem like much, but it just felt more maneuverable and seemed to fit on obstacles better. My current rig is 77" wide and I wish it were more like 75" just so the tires didn't stick out so far from the body asking for a ticket. It also turns like the titanic, but the front spool and steering stops aren't helping me there.
If I ever get $$ together to put together a buggy, it will be about 105" 4 seater and probably about 78" wide on 40's. I think that is ideal for Utah wheelin.