Except maybe if those outages hit them at the worst possible moments of the month (just before a major announcement or something).

Now, managers would froth at the mouth hearing 45 mins/month is acceptable. But those managers are idiots.

I haven't seen any major site that didn't have those (and worse) outages.

5-6 hours a year? Heck tons of sites had those. AWS had them (and thus Heroku had them), GAE had them, Twitter had them, Tumblr (well they had one-two orders of magnitude more), etc.

45 mins a month represent lots of lost revenue to you? Really? If you're not Google or something, then what exactly do you do?

Shouldn't that be like 0.1% of your revenue? And that IF you sell online and IF we assume customers aren't gonna come back. Heck, you lose more because of random fluctuations in buyer preferences than that.