Load consideration

In everyone’s experience, what do you think hardware wise, considering the following, and what kind of load limit can I expect from the software?

I will be utilizing NAT and Rate-limiting functions:

Rate-Limiting on 22 - 24bit subnetworks

NAT on 18 - 24bit subnetworks

Ideally I would like to use 1 mikrotik server, but looking for opinions on hardware/software limits related to mikrotik before I have to split this load up among several servers.

Thank You,