Yes, The Revelation is a bit shorter after cinching. But, this was a known issue even a few years back. A few highly respected hikers recommended the long, wide to me several years ago when I was researching another bag. I tend to be a restless sleeper, rolling from one side to the other, often stopping on my back or stomach along the way. A lot depends on your sleeping style. Plenty of people are happy with a regular length, anyway, usually side sleepers as is the majority of the population. But, fully stretched out, on my stomach, with my head covered (except for my face) I find that the long (84″) is just enough and I am only 5’9″ tall. Again, a lot depends on your sleeping style.
Historically, unless temps dip below 20F, I never bothered with zippers, anyway, rather using the bag as a quilt…loose over me. However, the foot-box was shaped. I avoided bags with a differential fill (ie, much like the BA bags with down over you and only a pad keeper below.) A quilt was a natural extension of this when I was looking for a new bag between the Marmot 0 and summer weight 40F bags I had. Allowing 9″ for the foot box meant the regular would not cover my head. So, these calculations agreed with the recommendations.
I saw several people using quilts less than 20F, and several people switching at 30F to a full sleeping bag. It got down to 10F one night with my Marmot and realized that drafts would be a problem at 20F and below. I usually zip up my bags at near the lower limits. Especially, because I roll around a lot, I went with the wide width. (I also purchased a Hoodlum, but never needed it.) I see Tim updated the web site to insure people know about the length allowances needed for the sleeping style an individual uses. I am not sure when he did that. This is just a series of notes, not an actual chart on his site. An allowance chart for sleeping style would be a good idea for any quilt manufacturer. If he doesn’t already have one, a chart for recommended Insulating Values for pads would also be a nice add-on. I found my old pad at R3.2 wasn’t quite enough at 20F and needed a slightly warmer pad (R4.0 or so.)
But, you might be able to trade up to a long for near the full price applied toward the new one. Of course, a certain amount of shipping/handling still needs to be applied. Check with Tim (EE) to see if he will do that. He doesn’t seem to have any problem selling used quilts. Or, try to sell it here and purchase a long one. Those things can happen easy enough if EE also wishes to maintain their customization line.
To me, opening the foot box would not be the best option. I would pay for the couple ounce increase for a longer quilt.