Below is the list of hosts which we have found compatible to WPMG. We have also listed good and bad points of each.
We recently switched to Siteground and discovered that it has one of the fastest servers in industry. The TTFB (Time to render first bit) which is a very good metric to measure server speed is under 200ms, which is great. The security is tight and they manage to keep the uptime to 99.9%. Overall, switching to siteground was a great experience. We hope that the everything remains the same in future or gets even better. So, there is one thing I can say very confidently to you after my experience, that is, Siteground is awesome in terms of speed, cache and uptime. It can run WPMG very well, without any problem. And please do not think we are promoting siteground because of our referral link, we got referral links for all hosts ; ) .Siteground has undoubtedly proved itself best for us till now.
Not found anything bad as yet. But we will keep a watch and will update if anything happens : )
Namecheap provides all functions needed to run WPMG. It allows sending emails through wp_mail. Namecheap is for someone who is looking for hosting in minimal price. I have found namecheap to be one of the least expensive hosts.
They have a medium level speed, not fast but not very slow either. So if you think a normal/average speed is fine for you, go for namecheap.