You're right that clock speed is much less of an objective measuring stick than it used to be, so that complicates any recommendations we give.  Additionally, variations between repositories and usage patterns will have a huge impact on the resources required, and that's before you consider the several orders of magnitude variation in user count between organizations.  Some workloads would benefit from more cores, others from faster ones - and that's assuming that your workload is running into any kind of ceiling.

So definitely take those numbers with a grain of salt.  If this is a new installation, you can start with the hardware you have available and see if it's sufficient.