Richard Lee, in his handloading book, states that their bullets are guaranteed round to within 0.001" (and stated size +0.003", black powder bullets are stated size -0.003"). I'm assuming that this means round balls are also within 0.001" of stated size (doesn't say anything to the contrary that I could find).
I have several Lee RB molds, and all have been acceptable EXCEPT the 0.490 that was undersize and out-of-round. I came across someone else who had the same problem, same mold. As for customer service, it's inconsistent (particularly if you're overseas). I can honestly say that in my case their customer support (and concern for a customer) is woeful, which, by the way, is contrary to everything that Richard Lee states in his book as he always put the customer first. Pity son John doesn't appear to share that ideal.
The one advantage you have in the US is that if you should get stuffed around by them you won't be out-of-pocket by much, given the low price of their molds.
Oh, and I also have a mixture of the old and new design of block alignment, and must say I prefer the old style.