I have the QU-AX and I like it very much. Although the DX is cheaper, it has shorter cranks, which I don’t like, and it only comes with a 2.6" tire. I think the frame will fit a duro, but it is not stocked. The DX is a bit heavier, but it’s pedals are better. Both are good uni’s but I prefer the QU-AX. Hope this helps.
I think the Qu-Ax and DX are pretty much identicle except for its frame, the DX has a weak frame that will brak within about 5 months of hard use, but can be replaced with a 42 dollar Nimbus II frame. Which I think, still leaves you cheaper than the Qu-Ax.
If you dont want to replace your frame, just buy the Qu-Ax.
Not to bag on Mornish, but a) he’s publicly stated that he posts as often as possible even when he doesn’t know much (if anything) about the topic, b) he’s only 12 years old, and c) he only weighs like 80 pounds, so his judgment about durability etc. is based on his own body weight (or lack thereof!). He seems like a really nice kid who loves unicycling, but I don’t think you should take his opinion on products as particularly compelling.
i went through the same dilemma when i got my first muni, and I decide on the qu-ax. it’s a great uni, the only thing is it’s a little heavy, but it’s solid as a rock.
some great pluses are that the qu-ax comes stock with the 3.0" tire, and everyone i show it to loves the 45mm (really wide) rim. however, the seat is pretty firm. the dx is cheaper and lighter, with a cushier seat, but i haven’t regretted getting my qu-ax at all.
oh, and the cranks: the qu-ax’s 170mm cranks are a dream when climbing hills, offroading, etc., but a little more work on flatland than the dx’s 150mm. so, that aspect depends on what you’ll be using it for.