And like I have said before, your mileage may vary.
I have some dreads, a load of eldar stuff, a Valkyrie and other assorted odds and ends, and haven't had issue except with one of the Waveserpent kits, which was easily fixed. In our group we have a couple of the daemons and assorted super-heavies and few problems. If any it is mostly due to normal casting process issues. So our experiences are quite different and I willingly buy from them.
Everyone tends to have a different opinion depending on their experiences. There tends to be a lot of Forgeworld at our shop because of the good experiences.