I usually leave an older version on for up to 6 months, then I kill it.. I figure I've found what bugs I need to find or they've been patched by then and I've got all my previous release stuff swapped up..
Doesn't help with LDD 2007. They made it so that once you open a drawing in 2007, the drawing is incompatible with all previous versions (even after an Export to 2004 or 2000). There's no reasonable explanation for this, since they made no functionality changes in LDD 2007 (or LDD 2006, or LDD 2005...), except maybe they want to annoy everyone into getting off of LDD.
And installing LDD 2007 breaks Lisp access to LDD 2006, so simply installing LDD 2007 really causes problems. That may be why they couldn't find anyone to Beta test it... (or maybe they didn't even try...)
