How many plugins installed and running?

I did a search for "number of plugins" and "how many plugins" but I didn't see any other posts on this topic. Forgive me if I missed it.

WPMUDev has over a hundred plugins and while I don't want to use all of them, I am interested in 20+ for my new MU site.

I've also seen a number of articles (including this one: on how installing even over 10 plugins can start to slow your site down and requires some techniques to mitigate the slowdown.

So how many plugins are you running reliably? Did you need to follow the advice in that article to speed things up? What are the limits with the number of WPMUDev plugins?