The best I've come up with is, NEVER EVER remove a page, DEFINATLY NOT if it lists well. DONT change it, or move it.
COME ON HERE, the game is to get a GREAT listing. Now that you have it you want to get rid of it? I have pages I tried out over 2 years ago that never got into the top 200......... a couple of them now, for some unknown reason are #1.
Ok, so you want to totaly redesign your site. What do you do with the old pages? Leave them, and put one large graphic (400 x 300 works well) at the very top of the page that says, "This page has been redesigned and Moved. Click here for the new page".
Yeah, you might lose a few people that think it's not professional, BUT you'll gain a LOT more from the extra listings in the search engines.