The heavy duty companion is a thicker blade but I can't remember if the tang on that one is the same or more robust than the original Companion. I remember the Japanese man who has hundreds of Bark River knives and does extensive video reviews on youtube once did a review on Moras. It was cool, he is some kind of a doctor so he took a bunch of different Mora's and x-rayed them at his office and showed what all the tangs looked like inside of the handles. His channel is called Virtuovice and it's worth a look.
As far as trusting my life to a HD Companion I'd say no. I would grab my Garburg if I were to use any Mora as a survival knife. Mors Kohanski has good videos on youtube under the Karamat Wilderness Ways channel and he gave the Companions fair reviews but did say that students broke them at times in his classes due to the partial tangs. The HD Companion still isn't full tang so I wouldn't want it to be my only knife. I keep mine in my day hiking/get home bag but I don't really use it often.
I have an Architect Field Buddy 5.5 that is my trusty woods knife. If I'm going out in real wilderness, especially solo, that is coming on my belt in a Spec Ops short combat master sheath.
I got a kydex sheath made for my Garburg so I can wear it upside down as a neck knife. It's heavy, but if I put my hood up and then put it on it's fine. Sometimes I wear it like that just around camp or in the woods on the property where I live, but not for long periods of time. I have the leather sheath for my Garburg and I like it but found it kept coming un-snapped on me.
The HD Companion could probably take quite a beating but I've never destructive tested one so I don't know how much it can withstand. For any real hard-use knife a full tang is a necessity for me, but the HD Companion is cheap so you might want to get one and really pound on it and see what it can take. Maybe you'll find a place for it or at least get a good idea of how far is too far when it comes to pushing the envelope with it.