I saw them many years ago at Frankfurt, Rheuben Allen had a few straight tenors (and altos), interesting though they are I think that the great majority may buy this for the cool factor but never really play them outside of the occasional gigs to show the sax off. Of course they all came from the Buescher idea (which also produced a straight baritone) and since then the idea, in practice never took off.
One of the probrems are indeed the very long rods, prone to flexing , I remember that I commented to Mr. Allen that it may be wise to detach the link of the G# just to lighten the action of the rest of the pinkie table ( as Couesnon did in their horns).
Aside for the playing problems ( how many time will you bump the bottom of you saxophone onto an object that you don’t see?) there is another serious problem, if you play with a microphone or you are recording where are you put and how many microphones will you need? If you are playing like the lower nots are going to be directed onto the floor.
But, other than that, yes, very cool.