Down time complaints are legit, however fretting that you are missing the the few hours out of 2160 hours... seems a bit overboard to me.
That's a .02% chance of missing the prized bot if the downtime is 5 hours out of 2160 hours (3 months).
There are better ways of getting your site in the indexes than worrying about that .02%.
However being down for 5 hours, for a site that generates revenue, shouldn't be something you need to tolerate. Sure, there will be times when downtime is unavoidable, but your hoster should be able to mitigate most issues and recover faster than 5 hours on average.
WHT is replete with stories of one host down or another for extended periods of time. Its clear from reading a lot of these stories that some of these hosters have little redundancy or experience in planning for and dealing with downtime.
Contrast that to a big experienced provider:
Notice how very few of the outages are for more than 10 - 15 minutes? And even for the truly serious outages, the hoster was able to deal with them in a straightforward professional manner?
Forget 99.9999% guarantees - nothing can be guaranteed with certainty. IMO its more important to see how hosters deal with problems than to rely on some arbitrary % of uptime.
I really believe that penny wise / pound foolish for a revenue generating site is a good rule of thumb when it comes to chosing a hosting partner. It costs real $ to have quality machines, network, spares, people etc.