Perhaps if you added your actual volume numbers to your entry it would help the conversation? I have several sites on various platforms, and I'm currently running over 160K visits per month across all of them. It's not unusual to have 10K visitors from HN drop by on any given day. I haven't had any problem with WP. Of course, I don't really check it. It just works.
I hate to sound non-caring, but is it really a problem if ten people come by your blog at 3am and can't load the site up? They'll be back at 4am, and the site will be fine then. Do you really need 99.999 uptime on a blog? It's all a numbers game. If you lose 2% of visitors due to technical problems it shouldn't be a huge deal. Just take a look at your funnel and conversion numbers and do the math. There's no way that damage is going to come out to $2500 per year.
On a personal note, what I find is that there are a huge number of opportunities for my startups to accrue costs that don't justify the benefit. It's tough figuring out what to spend money on. Things like hosting or tools have to pull their own weight.
ADD: There are a lot of companies that made huge amounts of money leveraging free blogging services. Not my cup of tea, but it does provide a bit of context.