Steve, I can see where you are coming from and other peoples experience is always appreciated.
You can probably tell I get a bit edgy about this subject, as you are not the only person I've heard who reckons only 20hp is the limit from cams. A lot of these other people are people who have been following 'Peter Scott's' car. He only got 10-15hp out of cams, but he only got the exhaust cams done, and I'd say he only got an extremely mild regrind done on them. Unfortunately a lot of people have taken his results as gospel, and have come to the conclusion that cams do nothing.
That said, I would agree with you that if you put mild cams into the 1uz, on a stock ecu, and didn't get it retuned, that yes, you probably would only see 20-30hp increase.
However, if you get the ecu retuned to suit the cams properly, then that hp increase would dramatically rise (IMO)
I would also agree with you that any mild to serious cam would cause a lumpy idle and would not pass a smog test.
Fortunately for me, neither of these are a concern. The car I plan to get cams for is not a daily driver, and the state I'm in does not require smog tests.
I'm hoping to get some cams a little bit wilder than the 1uzquadcam.co.nz car's cams, hopefully in the next couple of months. I've been saying this for ages now, but with building a car as you can afford it things never go to plan.
I'll be sure to post some results when I get them, whether they be great or average.