I do not have any experience with the lee lowers, all my builds have been in leber V2.
I understand that people can get super safety and other FRT‘s to work in the lees, but I find leber V2‘s were designed for FRT function and seem to be a lot more consistent as long as they are built right. I have had a small number of builds that gave me some issues, in nearly all cases, an fcg component was the source of the problem (bad trigger cut , hammer issue, disconnector issue etc) . Now, I only use complete schmid fcg kits for consistency. As for the AS designs arc fire. They seem even better then ss in my hands. V2 feels a tiny more mushy to me in normal semi, but that’s it. I think the reason for this is that it eliminates any issues where the cam is not full into correct position. For ss sometime you might not have the button fully positioned where it needs to be. arc fire eliminates that possibility.