Any good for trials/street?
Not really. For trials and street you are going to be wanting splined hub and cranks. If you must use cotterless, then for street you are better off with cranks with no offset and for trials many people prefer cranks with offset like those. But really if you don’t need splined then you probably don’t need fancy cotterless either, so you are probably best off with some cheap ones that turn your wheel.
I’ve had a pair on my muni for the last year or so. I like them - they seem plenty strong enough and don’t flex like the standard skinny steel cranks (I never bent the standard ones, but found the flex a bit disconcerting). My riding is mainly cross-country, no big drops but pretty rocky in places, with the unicycle getting dropped regularly onto rocks in UPDs. They’ve got plenty of scratches, chips and dents but no sign of cracking - they’ve never even come loose.
If you’re light and don’t do any silly drops I would think they’d be as good as any other cranks for trials - as long as you like cranks with a bit of flare (that’s part of the reason I bought them, I kept hitting my heel on straight cranks). They’re certainly a fair bit lighter than steel cranks.
Rob