I've got about 10 lee moulds now. The only one I've had any major problems with is the one for 45ACP. The bullets will NOT come out round. Everything lines up and works smoothly....it's just the mould wasn't made straight I guess. The others work ok. I've just bought my first Lyman steel mould, but haven't received it yet. Looking forward to trying it. 9 of my lee moulds are one or two cavity. I've got 1 that's a 6, and I have to agree, there is a difference in quality.
I should note. My heavily used lee moulds have 2 problems. After a while, even with lubing, I start to get a lead buildup under the sprue plate that I have to scrape off every once in a while....500 or so casts. This buildup slowly wears away at the top of the mould. This causes a gap to develope between the sprue plate and the mould surface. After a while, you'll start to get a bit of a razors edge developing on the bottom of your bullets. This can easially be removed with a scratch from your fingernail, but does get thicker as the mould wears. Eventually, it becomes to be too much of a pain, and the mould gets shelved.
The other problem is binding in the handles. I've got 2, that no matter what you do with that damned nut/bolt, whether it be loosen, tighten, or lube, they get very tight after a while. This comes and goes. Some casting sessions, it's fine. Others, it's a fight from start to finish. I haven't taken one apart yet (just lazy) to see what the problem is or how it can be resolved. It's not a complicated device, so the fix is going to be pretty simple.