Well, I finally got around to doing this tonight. I had the house to myself for a while tonight, and I was waiting to clean the gearbox and replace my opto board with the one with the integrated "Leon" fix at the same time. (https://pinside.com/pinball/forum/topic/tom-trunk-error-leons-fix-anyone-done-this). Anyway, my grease looked nasty, but wasn't like "taffy" as others had described. It was definitely thicker than the grease that I replaced it with (the "Super Lube" as shown on page 1 of this thread).

Anyway, I have before and after photos. I might have gone a bit crazy with the fresh grease, but it seemed like about the same amount as what I removed, but just more evenly distributed.
nasty
all freshened up

Honestly I can't say that the trunk moves any/much faster as it never seemed slow before, but it was just a matter of time before the old stuff got stiff and became a problem.