I personally did blow one Ronstan block in my 10 years of sailing. It was one of the first series ratchet blocks. It had an issue that was recognized by Ronstan and they redesigned their ratchet blocks. They replaced my old block (broken) with a new one.

All the other harken blocks seem just fine to me. Same for Harken. I do have some misgivings about the way Ronstan designs their mainsheet systems but that is about it.

I'm using small Ronstan blocks in my cascading downhaul system and they have held up perfectly over the last three years of sailing. It is a 12:1 systems and blocks are loaded up passed their SWL.

Having said all this I think that my boats do tend to see lower loads then Tornado's or Andrew's (Macca) Super Taipan 5.7. Maybe that is the reason Ronstan fittings are just fine from my perspective.

Wouter