We have two hosted instances, each on the business plan. We were an early user and appear to have a significant discount.
We spend little time on administration. Discourse's spam filter seems to work well. Sometimes new users posts will get flagged and you get pinged and have to click something. For major problems, Discourse staff (shoutout @neil) is responsive.
It sounds to me like you are leaning toward running it yourselves, but if you have budget I'd recommend using hosted Discourse. Maintaining your own infrastructure sucks.
I've been happy with both the product and the team behind it.