Friend of mine has a pair of these (I think they are TL28s) in 26in flavour and over the course of a few rides on averagely rough terrain has reduced them to tin foil levels of crumpled-ness. He’s on the forum so may well be along shortly to expound a bit…
Indeed, my rear one got 5 sizeable dints on its first ride but only on one side of the rim (got one on the other side on the second run).
However, I emailed the guy at JRA (Jon I think) and he’d been testing them for a while and only damaged them on a rocky DH race so I think my rear one was maybe a dud. JRA have kindly offered to replace with an arch ex so I’m happy.
My front wheel has been fine though, even on some pretty rocky trails that I rode after swapping in my 819 wheel (bloody heavy) on the rear.
I’m not the type that notices stiffness/flex so can’t comment there.
Oh and they seal up pretty easily tubeless. (I use a 2.35 xr4 on the front and a 2.25 Rocket Ron (new pacestar type) on the rear)
Sorry, I didn’t weigh it unfortunately. Just as an aside, check out spank’s new rims since they started getting stuff made by ‘fratelli fabrications’. They seem to be remarkably strong for their weights given a few people’s experiences. Spank supply tubeless tape too.