I see there is a limit in the inputs.conf (1-9) but what about the serverclass.conf file? There is no mention in the documentation.
Here is the spec doc for the serverclass.conf file.
I have not run into any limits on the number of items. Especially when I use a csv file to specify 100s of servers for a specific class. You should be good.
So far from my experience there is no such defined limit in serverclass.conf, neither have I faced any issue related to limit in serverclass.conf.
Also, in case if you faced any such issue, I would suggest using "inclusive" serverclasses.