||I've been running these both sides for about a month now and they're pretty tough. They slide well on rails and waxed ledges, and are well sized in terms of diameter, so as not to be too bulky but give enough coverage for the hub flange and spoke elbows.
Fit: I have had to spread my forks ever so slightly to fit the wheel in, but that's not a bad thing, everything is good a snug. I'm running a female front hub, and all works well.
I do find myself hanging up on the guards from time to time on double pegs and smiths, but that's probably more to do with me.
Heat treated 4140 is probably going to outlast me. I wanted to switch to chromoly guards as I don't like the idea of contributing to more plastic waste. These are pretty decent, fairly priced if you consider they'll outlast plastic guards several times over. My experience of Eclat is that they make great, well conceived and engineered products.