I've run a 180 SC2 Supercorsa and then a RS2 Rennsport on my Mag Marchesini 6.0in rim...the turn in is noticeably quicker than the ol' 190 I previously used.
I was told that fitting a 180 to a 6in rim would have the effect that you mention (flattens the profile) but I thought I'd give it a whirl and, yea, I did it and it was good.
Give it a whirl...what's the worst thing that can happen.........
...another muppet award????
Oh yes, I also run the steep head angle and have raised the rear...what's a bit of liveliness if it ain't a bit of fun???
[Edited on 7-6-2004 by RickyX]