RB1000 hotspot: how many users

I did some searching, but was not able to come up with much.

How many hotspot users will an RB1000 support? System will be connected to two DS3’s, with a separate Radius server for user authentication.

I know that a software limit won’t be an issue, I just need to know how much the hardware can support before it becomes bogged down and performance/stability becomes an issue.