[macspoofing]

No, what he means is that Page.ly went above and beyond what is reasonable for the price you're paying them. Yes, it was very nice of them, and most likely they did it because they are a young and hungry company. At the end of if all, I don't really get a sense from what you wrote that WPEngine service was terrible. It sounds like you were a difficult customer with difficult architectural issues that were ultimately the root cause of your performance issues.

[jacques_chester]

I don't see how an ordinary multisite installation -- which they specifically namecheck on their website -- is a "difficult architectural issue".

[grey-area]

It it really an ordinary multisite install though? Do you have 188590 comments? Wouldn't you have trouble with any hosted providers if you are doing operations on that many records in memory (whether that is the fault of WP, or custom plugin code, it doesn't really matter)? If that's the case, it looks like your site just isn't a good fit for this type of service, but millions of others (including multi-sites) with say a few hundred posts and a few hundred or perhaps thousand comments are.

It's a shame that you had to go through all of this trauma to discover this, and there are obvious support failings here, but it does seem that your site is out of the ordinary in some respects, just because of the number of comments on one WP instance.