For anyone interested, mountebank[1] is an also-good OSS alternative in the same space
I tried using wiremock for mocking HTTP requests to our microservices' downstream dependencies. Rather than using a standalone wiremock server, we used the java lib. Periodically the connection would drop and our tests would fail. Switched to a standalone mock and haven't experienced this issue since.
We did run into an issue a small when we parallelized our tests. After a certain parallel factor we saw what looked like Wiremock not being able to keep up. However this might be FUD and we were running these tests all on one machine including a docker-composed test harness so there were a lot of moving parts
Overall Wiremock is excellent. I really rate the functionality to attach state to scenarios. You can model quite complex behaviour with this