I have a 3 element steppir that I installed in 2002 here in Arizona. I have put a coat of fiberglass paint on the tubes once. Other than that, its never failed or caused any problems. I have found it to be the best 3 element yagi for my needs. I work the warc bands quite a bit and like the flexibility that the steppir offers.
I have assisted in putting up a number of steppir's (DB 18E's) and all have performed flawlessly. I have heard of only one ham that had a problem with his steppir and that was due to not following the assembly instructions.
I am in the process of assembling a SteppIR DB36 antenna and I guarantee you that it is quite a complex assembly. I can see where some one will try to speed things up by cutting corners and not following the instructions diligently and that can result in failure. Like Steve said, all moving parts are enclosed and if done right will work properly and like everything else failures can still happen. I also got the 80 and 6m options and hope to get it going soon. Been at it for 3 weeks now. Having looked at a friend's DB 36 up at 70 feet on a windy San Fernando Valley location, I am making a few modifications of my own to stabilize this monster to keep it from bouncing up and down on windy days. It will be mounted on a 72 foot crank up tower and turned with an Orion 2800 HD rotor. The people who own Steppirs I know all said that proper assembly is the key and you cannot rush into just getting it done.
73, Gurbux. W6BUX
No personal experience with StepIR, just the same anecdotal accounts of failures and down time for repairs that some others have mentioned.
Count me as another vote for Optibeam -- substantial aluminum stock, quality stainless fasteners, built like a tank, stick it up in the air and it works, simple!
James - AD1L
Please accept my gift of bacon