My SPC's have held up pretty well and I slam the 4Runner around enough to put a few good dents in my new RCI 3/16" steel skids.
The first set I had the bushings went out in a little over a year or two (this was the set I bought about 3 years ago) and SPC sent me an entire new set of UCAs, the current ones have held up fine and I haven't had any issues, they even have longer upper ball joint boots (the old ones did not and it concerned me in dusty/dirty environments.) That being said I have seen one set actually crack at the welds and just make a mess (part of it was the driving style/improper approach/over burdened suspension set-up on that vehicle/driver, the other part was a very probable welding defect when I looked at it.) Though I have seen a few more cases of failures from mild to severe off-roading, which in my opinion is a bit on the high side for a product intended for off-road use; but conversely SPC has been very good with their customer support and they seem to actively be fixing their product for what its worth.
One of my personal favorite things about the SPCs is how well they adjust in terms of correcting alignments, their upper balljoint set-up so far is a much better solution than most of the tubular designs.
All that being said, if you have an extra hundred or two and you really intend on slamming your 4Runner around; I'd go with some nice tubular set-ups. If you're mainly just looking to correct alignment after a lift and mainly do on-road driving I don't think the SPCs will hurt and they do a good job there. I personally will be going to a beefier UCA later down the road, but so far I haven't had an issue with my set and my typical off-roading mentality is: "the mountain will either stop me or crumble under my 4Runner, one way or another I'm going THERE!"
Post Note-
The SPCs have garnered a bad reputation (not undeservedly so) and it takes a while for companies to recover from bad reputations, even if their product is 100% flawless NOW (not saying that they are, just saying that even if they were the best on the market NOW, people would still be wary/uneasy); its a natural reaction from people. Its not bad or good that people still bash on them, even though it seems their quality has gotten better, its just one of those things that takes time to sort out and many people would rather err on the side of caution and history and I genuinely can't blame them for that. All I can do is play devil's advocate and say, "well my new SPCs haven't exploded and killed me yet and they do well with how abusive I am off-road so maybe they're getting their shit sorted out?"
