Being in Alberta I'm not much help, and I know you said you did tons of research so you probably know most of this stuff already, But, I'm stuck at work waiting on a phone call so I figure I'd jump in and share some of my own observations and opinions on this tent as we've run it for 3 years of light use and things to look for in a new or used Smitty tent. For health reasons (I've been pretty sick all through the last year) we haven't really used it as much as we wanted, but I'm getting a much better impression of it.
Overall, my opinion is unchanged from when I first bought it -- for light duty touring, the Smittybilt RTT is probably the best value tent on the market. You get about 60% of the initial quality of the Tepui or CVT for a far smaller cost (about half here in CAN), and the Smitty comes with nice bonus things like lights and USB power that you can run to a 12V and an included shoe bag that my first tent (a Tepui) did not have, and those are nice features so if buying used make sure they include that stuff! That being said, this is not a long-term tent though -- I'd say it's a 5 year tent with reasonably good upkeep. The Tepui I'd put at a 5-10 year tent depending on maintenance, but because the Smitty's materials are a bit 'cheaper' all around, maintenance is only going to go so far.
That being said if you DO get to take a look at one (especially if you are buying used) there are a few weaknesses to take a look at. Even new ones, look at these things, because the QA/QC from the factory is sometimes poor. If you get a good one, it'll be great, but some come out of the box with a few issues that you should check on.
1) The aluminum bar that supports the overhang over the ladder is very weak. The mounts are not attached super well, and our bar actually broke under a small snow load. This is not a winter or shoulder season camping tent in my opinion based on my experience with it. New England gets a lot of snow so something to look at if you are buying this tent used is if the bars have any bends in them. They don't need to bend very far (less than a few centimetres) before they snap and break, and even if you don't intend to camp in wintry weather, if they are a bit bent, it'll greatly increase the chance of a failure due to wind, tree branch, etc.
2) The interior bars are made from the same aluminum tubing as the overhang bar, so that is another potential weak area though it seems that they are better supported due to the straps and fabric of the tent. Still, check them to make sure they are true and strong in a new or used tent.
3) The PVC rain cover straps (Not the rain fly on the tent, but the tent cover used when folded) are very poor quality and several of ours snapped. We replaced them with cam-lock tie down straps from Home Depot for about $25 CDN for all 4. I would make this change to ALL my RTTs in the future because the cams are way faster and easier to tighten.
4) Make sure that you have the chance to open and close the tent to ensure everything lines up. Because of the width, the tent gets a lot of structural integrity from where the fold meets in the floor when it's open. What I mean is, when you fold it the tent is essentially in two halves. Where those halves meet is a tricky spot -- on one half, there is a channel, on the other half there is a ridge that fits into that channel when the tent is fully open. That ridge has to fit fully into the channel, or your floor will bend and it will never quite fit in the channel in the future, and the bend will get worse and worse. So, make sure that the ridge locks into the channel before putting weight in it.
For less than half the cost of a comparably sized tent, the XL is a good buy for weekend runs. I wouldn't buy ours again, because we have bigger plans that will require something more robust, but if I was doing weekends in the mountains only in the summer, then I'd make the same choice.