The company I work at imports these. At all 45 suppliers you will find offer repro cylinders from the same source.
We have sold hundres so far. mostly no problems regarding fitting and wear.
There is just one issue that occured with a certain batch of front cylinders where they did the spacing wrong for the front valveguids. This leads normal valvesprings to jamming up the complete engine, destroying it if you try to start it that way ( ofcourse you can just locate the problem easily by hand cranking the engine as any good mechanic would do..).
I have been building a WL myself with a repro set of cylinders this winter, and I was lucky enough to get one of these wrong front bastards, and after some fiddling it turns out that a WR racing valvespring WITHOUT spacer gives the perfect fit on these wrong front cylinders * again, they are not all wrong, just some from earlier batches, and yes they are still in circulation...
For the rest these cylinders are as good as original to my knowledge.