Don’t know if it will help, but I run at one client a normal RB411 (no, not R411A) with level 4 license upgrade with about 30 users (up to about 10 or so online simultaneously) and apart from historical data filling up the store every year or so, the performance seems ok with the speeds we run at.
Ekkas
My 450G is my PPPoE server, usermanager, firewall, etc, and at 200 users I’m averaging about 10% cpu usage. How much total bandwidth do you expect? That could be the big factor.