Indeed. Shutoff Garbage collection completely and it can work. (And make sure your Java code creates no garbage - which is a new type of programming in and of itself)
This is incorrect. Firstly, C4 triggers two types of safepoints: thread-local, and jvm-wide. The latter can easily go into the region of ~200 micros for heaps of ~32GB even when running on fast, overclocked servers. Secondly, the design of C4 incurs performance penalty for accessing objects due to memory barriers. This impacts median latency noticeably.
You might not believe me, but ask Gil and he'll openly admit it. This article was written by someone who:
1) doesn't know how C4 works
2) doesn't analyze relevant metrics from their JVMs