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.