I had the Ironman kit on my old Xterra and had no real issues. I was looking for a budget minded setup at the time, and by luck bought the last kit from the dealer in Calgary (the feeling I got was that they were closing up shop....not 100% sure though) for a price I could not resist.
The rear leaf packs were easily as stout and beefy as the OME Dakar packs I have in the Tundra. I had the HD coilovers on the front of the Xterra to deal with the added weight of the bumper and winch, and while the ride was very firm I never had any issues. The Ironman shocks did start to show some signs or a little rust here and there, but nothing out of the norm. The rear leaf packs on my old Xterra chirped and complained for a while (though I think it may have been due to a crimped bushing sleeve) and they defiantly started to show signs of external surface rust, but they never sagged under load or failed to do their job.
The Ironman setup I had was certainly a no frills basic non-adjustment type setup (similar to the OME I imagine). I went a little different route on the Tundra build as I had some extra $$$ to budget. Time will tell if I made the correct choice in choosing the ADS Racing fully adjustable shocks.