John,
Anecdotally, I can tell you that in my hometown, both Holston Hills and Cherokee CC went through extensive tree removal. I have hovered between a 1.5-4 handicap for the last 7-8 years and my scores are virtually identical from when there were more trees on both courses. In talking with head Pro, Chris Dibble (Holston) a few years back, he said something to the affect of..."you would think the course record would have fallen many times over but it has remain unchanged since the restoration was completed". I speak to both Chris and Ryan Blair (the Superintendent) on a fairly regular basis and every time they host a big event we joke that they must be on '59 watch'.
Oddly...I just played Tennessee National today (Norman design) and it has virtually no trees, 50-60 yard fairways...and to me it plays as hard as any in town. When you poll the local yokels on what is the best course, most say it's the Norman designed Tenn National, while the same people decry Holston for the tree removal, saying "they ruined the course, too easy". My next favorite question is, "isn't Tennessee National too easy" (since it is essential wide open)? I always get a blank stare.
People that defend over-treed arboreums do it for two reason[/size]: Ignorance and ego. If the course is wide open and they play bad, they stink. If they play bad on a treed up course, their ego is preserved because it appears hard.[size=78%]