If you have the resources, you can always overspec the MM. It won't hurt, just requires more CPU and RAM. I don't have an answer for you on what is required for your needs, sorry. Also, if you build an MM, there is an easy process to do an in-place upgrade of the VM hardware to make the MM a larger more powerful machine. I think I wrote about it responding to someone in a previous question. The VMM does need to be taken down for a short period of time, but it is a quick, straightforward process.
I hope this helps,