On en.wiktionary.org, the broad majority of sysops use the feature in [[wikt:WT:PREFS]] to override the deletion message unconditionally, to prevent libelous information from appearing in the deletion logs. Since our deletion logs ARE harvested, it seemed rather prudent. The only sysops that don't have it turned on, are sysops that essentially never delete stuff.
With the appearance of the deletion log on deleted pages, we're revisiting how we handle misspellings. It would be nice to know if this lovely new feature will stay around long enough to make a decent test of the new method (not yet started.)
On another note, the fantastic mechanism now in play for "Block messages" is, I think, a superb template for how Deletion log comments should be entered.
--Connel MacKenzie http://en.wiktionary.org/wiki/User:Connel_MacKenzie somewiktadmin@gmail.com