Doc,
I still like it. I dug mine out and compared them. Mine has the extra quality private purchase liner (more fingers and square cut ends) which makes sense as it is labeled to a One Year Volunteer, while this one has the issue liner. Mine does not have the piece of material between the liner and frontplate. Perhaps this was inserted for comfort, or to reduce the size. Remember, these were introduced early in the 19th century, so they were in use for a long time. The rivet on the chistrap would seem to be a repair. One test of originality would be head size. You had to be a big boy to get into the KAR, mine fits my size 7 1/2 head perfectly. I have a Garde pickelhaube marked to the KAR (same company no less!) that also fits me. No pinheads in that outfit, at least until they put the helmet on. I would be interested if anyone knows the height requirement.
Construction details appear identical to mine. I see a lot of details I like, such as the dark blue trim material sewn between the frontplate and body, and the subtle mothing.
If you have a copy of Rankin's book, there are some sharp b&w photos of one of these.
In my humble opinion, based on the photos, this is an original issue piece.
Good Luck!
Steve