at the risk of flogging a dead horse I'll cite Star Trek again. Trials and Tribbleations had no new footage of original series cast members in it, Flashback did, yet I know which was the more enjoyable, and the more reverential.
That's a fair comparison/ example, so I'm not tired of you mentioning it again. However, at the risk of pre-judging the anniversary special, none of the Trek 30th specials dispensed with the TOS crew and opted to introduce, e.g. James Caan as an Enterprise Captain we'd never heard of before!