If you're going to do a guild wipe, just know that all current participants deserve to have themselves and their guilds records saved into a secondary leader board that it archived. As many players have spent countless hours, months and in some cases as long as a year to up their Gp's etc. This cannot be an excuse for a guild wipe, only to get more activity, which is the aim of the game to ultimately have fun... so ultimately im for the idea, if you can archive the current records into a new leader board.
Like the world cup... you're are a winner and in 4 years you might not be champion, but your legacy remains.