"...it's only affecting 30 or so sites but they are important, high-traffic sites and being offline is damaging to them and us.""
I'd have thought that if you were stung once with a server outage you'd have made plans to keep a mirror of the site for such events?
I only wonder about this statement because I host my company's sites on Linode on two VPS's on there. But I have these sites mirrored to Digital Ocean. I do this because Linode were out for a week once and it'd hurt our business massively if that happened again. It does cost a bit of money to do this, but it pays for itself in times of crisis. We joined Linode after this event, and thankfully they haven't had problems since. But I know it could happen again, and if you work on a site that turns over £500,000 of sales per month one day of outage will affect you massively.
It's 2017, the idea of having one server for one website and hoping for the best that it doesn't go down is long long gone. I feel for the customers involved, but Jesus H Christ if your site is so bloody important have a back up plan!!!!!