It's a great upgrade for that press.
Buddy of mine updated his press with one. He had to tweak it a bit alignment wise, but once he got it set up correctly, he was very happy with it. Here's an actual quote:
"The Safety Prime system came along and
dramatically upgraded the throughput of the turret press."
I've used his press and based on my own experience with the Safety Prime and Pro Auto Disk on his press, I'm buying myself a Lee Classic Turret press next month.
I highly urge you to upgrade. The thing works like a champ.
Dave