Another annoyance is how little it gels with the rest of Pages. I'd expect that if I'm developing an application from the ground up in Pages, incorporating the various Cloudflare value-ads should come relatively naturally. Instead I need to have entirely separate projects just for these components.

I forgot to mention about pricing. We've taken the approach of estimating a "worst case" time per object and requests/second rate. E.g. we assume a worst case of 30 req/s for the lifetime of the project, based on 3 users simultaneously sending updates at a rate of 10/sec each. And maybe we assume 1-2 hours of cumulative time spent in the editor per object. Multiply that out to get a value of GB-seconds per object, multiply by the respective prices, and add to get the total "expected lifetime cost per thing".

(We're not actually using durable objects' built-in storage, so this would indeed be complicated by trying to price that in. We only wanted DOs for coordination.)

If it's hard to estimate the total lifetime of a thing, you could estimate against something like how many hours can/will each user spend in your app per month, and come up with a monthly benchmark price. We haven't done that as the objects we deal with have naturally limited lifespans, and our pricing is tied to the number of these objects created anyway.