First off, I can't comment on the Lyman, RCBS or any other mold except Lee, because I have only used Lee molds.
I cast .440, .490 and .535 dia balls, .575-500 grain dia Minie, .458-33o grain and .458-405 grain bullets.
I have cast at least 300 rounds in each mold and they are all working great.
I will say that I seem to have better luck with the single cavity round ball molds than I do with the double cavity style. It's most likely me that's to blame but that doesn't change the fact that the single cavity molds seem to work better for me.
You might as well be forwarned though. This is another area of muzzleloading that can hook you and before you know it, your expanding your hobby again into more molds and lead pots and ...!