I used portrait mode mostly and in was pretty sturdy (enough to draw on) in the high angle ~60% mode. Landscape and low angle modes are even sturdier, so no problem there.
Even I did not try all the combinations yet! But if you guys are very interested, I will do a test of all the modes.
The construction seams between the aluminum "bones" (i.e plates) can wear out, but I solved this by sewing them in place. I can talk to the creator (he is on TabletPCReview forums) to ask for more durability details and construction changes for his newer models.
He hand makes each case, so he charges a large markup. I believe it is justified, considering his labor, materials and uniqueness of design.
PS. I believe the typical 12" case only costs ~$125 (which was the price of my EP121 FlipSteady).