I've owned a few, and used a few others elsewhere and I think their high powered tuners are a bit overrated for power handling, but actually fine designs. They're well validated designs. The only issue is material selection and workmanship. Problems do occur, but it's the luck of the draw. They're not assembled by robots. If they were, they'd be better. I'm not fond of Palstar after having some of their stuff fail. The Ameritron ATR-30 is probably the "strongest" manual tuner out there, IMO. Never had one fail, even through a lot of abuse and squeaking power above the legal limit (accidentally, of couse!) several times. Also true that tuners aren't difficult to homebrew. Very easy, actually. The trick is finding the right components. The "box" isn't important...my early homebrew tuners, even running a kilowatt, had no enclosures -- they were built on a sheet of plywood and worked fine. The "shielding" on a metal-cased tuner isn't so much to prevent radiation as to prevent the user receiving RF burns from touching stuff when he's transmitting.