Hi, MVF
Sorry, didn't see this post 'til a few minutes ago. Other than the HR surface corrugations, lots of similarities between the two. There's not a
large difference IMHO. Both about 3/16 thick, but the HR gets quite a bit of blade heftiness back by being 1/2 inch longer and about 1/4 inch wider. Along with a handle and tang which is a little wider and extends about 1/2 inch further than the SJTAC, there's a slight chopping advantage to the HR.
The way it boils down do me, then
biasing for my type of field work (I'm a fisheries and wildlife bio - always trying to build or tear down something out of brush and small trees):
SJTAC feels great in my hand and is a great 6 1/2 inch knife. I like everything about it :thumbup: . However, for working and making things in the field, I find it hard to beat the HR.
I think that the HR is probably underrated. Many of the Hogs don't seem all that excited by it. It has field utility written all over it without being so heavy that it will drag your pants down (so you don't carry it when you need it -- also, small enough, barely, not to seem like a "dude knife" to the uninformed

) Thin enough at ~3/16" to cut well; just hefty enough to chop ok; indentations in the spine fit my medium-large hands real well when I choke up and make it into a "smaller" knife for skinning; combo of dropped point, wide blade and indentations on the spine make it into a very good improvised draw knife, I've discovered.
Also, haven't tried it yet except on very small scale, but the shape of the HR blade is kind of like a small trowel which should work for those small-scale earthmoving projects, like digging your tire out of the mud when the mounties aren't around to rescue you.
Depends on your need, but you get some measurable extra utility without much added weight or bulk over the SJTAC. I bought a HR with regular scales, which is ok, but would probably get magnums if I were buying now (although small scales probably allow the knife to ride in the sheath a little closer to your body).
This may not be relevant here, but as I noted in another post - , IMHO, I think that the HR constitutes an excellent military field knife (expense aside, and for those who are willing to make room for it in / on their field gear), although some unit officers have biases against blades longer than 6 inches or so.
MVF, also, got your email, thanks for the info. I've replied by email. :thumbup: :thumbup: