I have the Hornady powder cop die on my progressive.
It is easy to re-adjust for different cartridges and gives me about the same check as actually looking in the case. It is about the only place that i like to use Lee o-ring lock rings because I can adjust the die without any tools.
I have not used the RCBS Lock Out Die, but reading the descriptions and instructions, it does not sound very easy to adjust and would be expensive to buy one for each cartridge that I load on the progressive. Currently, I load 10 different cartridges on my progressive.
Maybe someday, i will have some bucks to burn and will give one a try.