We used RabbitMQ extensively for almost two years but the problems we were encountering along the way weren't worth it. We ended up talking to the dev team too often to solve catastrophic issues that took down our whole production for hours.
We reconsidered using it again for a synchronous RPC communication as we were replacing gRPC, but ended up going with nats.io instead. It does have less fearures but we are able to squeze much more juice on a smaller stack.
gRPC is a great, but has a ton of small problems including a catastrophic documentation (in some cases we had to read byte code to figure out what to do).
The biggest issue for us was however was that there is no middle server that could handle an route connections to available workers. We were using haproxy which worked ok but far from great. It was very hard to figure out how many servers need to run at any given point and thus a ton of our requests were ending up with UNAVAILABLE response.
Essentially what we needed is a synchronous RPC over PubSub which gRPC doesn't offer.
We reconsidered using it again for a synchronous RPC communication as we were replacing gRPC, but ended up going with nats.io instead. It does have less fearures but we are able to squeze much more juice on a smaller stack.