I just got my grail rifle a shiloh sharps # 3 in .50-70. I have a lyman 515141  450gr mold but am wondering if going to the lee because of the second cavity would be any advantage other than a increase in production.

Ranch, thank you for your answer. I didn't even think about the heat issue but now I remember that the lee that I had with my navy model rolling block always produced frosty bullets. So I'll stick with the lyman which when is up to temperature makes nice bullets. 
Thanks again  Hawkeye

The Lee molds are economical for someone only casting a few bullets.
I love my Lee 12 ga slug mold.

However the aluminum molds end up scoring or easily scratched or pitted. 
Steel molds have a considerably longer life and are capable of casting of thousands of bullets without significant wear and tear.

I only use steel molds and good quality custom steel molds for competition shooting.

Lyman makes excellent molds for hunting and sport shooting but to produce higher quality bullets I have used Paul Jones molds (no longer made).
Brooks, Buffalo Arms and Accurate make good quality molds.
However I always ensure I have the proper length of bullet appropriately matched to the barrel's twist to ensure a suitable gyroscopic stabilty factor regardless of changes in humidity, atmospheric pressure, elevation or temperature.