What if the hassle simply does not outweigh the cost of the flaky VMs?

There are several reasons the hassles might not be worthwhile even if the free VM is 100% reliable. Most other VM hosts offer mostly Linux solutions and Linux skill is not always transferable to windows. If your organization has those skills then the wasted time cost might than a familiar VM would have cost.

You can run linux on azure.

I've chatted with people who've gone through Microsoft Accelerator, and that's exactly what they're doing.

Yep. Also I can confirm that for at least some accounting, MS treats the free credits as revenue. They will give discounts and consideration based on your spend even when the spend is just credit another dept gave out. Clients have told me of very happy calls from MS reps when their projected spend for the year exceeded 50K even though it was nearly 100% credits.

If you're going to do log processing, it means you've got data to process. And I haven't worked with AWS since 3 years ago, but in general external bandwidth is expensive, which is why you want to keep everything in the same data center where bandwidth is free and where you have no latency.

Good point. Agreed.

But, don't the free credit cover the bill incurred from bandwidth as well?