What many people seem to miss in these sorts of discussions is that "pauseless" usually also means less throughput. I guess it's not different from real-time systems being slower in practice than non-deterministic ones.

If what Azul has worked on conventional Client/Server-JVMs, Sun/Oracle/IBM would've adopted it long ago.

The sad reality is that spending 99% of your time in GC, but never in a pause longer than "x units of time" qualifies as "pauseless" and if you want more throughput, you have to scale up the system so that the remaining 1% of througput is sufficiently large for your workload.

I guess this works in the markets where Azul is active (things like finance) but is useless in more conventional use cases.