I did. Still fails - I can walk right over it, either with one block of soulsand or two.
(And, also, the design specifically says it's good for minecarts.
...aaaaaand I hate to do this, but is there any way that an admin could restore 10 levels of XP to me? I just discovered the hard way - and by "hard" I mean "TheBushranger aimed for the ground and hit" - that /warp dragontemple is (a) located with only air underneath it, and (b) enough air that it doesn't matter whether it's the fall or the sudden stop that kills you, you're just as splattered over the landscape beneath the warp point.