I've got a Mohawk solo 13 that says R-84. It cost slightly more then the royalex material when I bought it in 2012. It was stated to be a few pounds lighter then the royalex. I keep it hanging in the basement when not using it. It seems to be just as solid as the day I bought it.
Roy
R84 aka Royalite is a thinner (and lighter) version of Royalex. Historically R-84 boats were slightly less expensive than Royalex and definitely somewhat more "fragile". For both Royalex and Royalite older boats using Uniroyal made sheets are preferred over the subsequent Spartech versions (started in 2000). In both cases UV exposure is the thing to watch out for, I would stay away from any Royalex boats that have been stored outside and exposed to the sun for extended periods.
I have a Swift Raven in Royalite (R-84), I haven't used it for a number of years because it needs a lot of repairs (cracks) after using it on a couple of rough trips. Depending on your usage it might not matter.
I'm a fan of Mohawk, I have 2 XL14's and a Probe 12II but no experience with their dedicated Tandems.
If your use will mainly be flatwater with some easy C1/2 rapids it should hold up ok.
With the thinner Royalex should I be concerned with a pin?
Gentleman said it happened once. Canoe canted, filled with water. Got the packs out and everything seemed fine. Has used for some years afterward. You can see the dents below. Cause for concern?
I saw the gunnel divits, they are nothing. I have an XL14 that the right gunnel bent severely near the bow, I added an extra (short) thwart in that location in case I ever had a similar incident in the same location.