Is the G1 GC in Java 8 in general production level quality? Is the G1 implementation in the latest Java 8 service release (almost) identical to what is included in Java 9?

In other words:

• Is it a good idea to evaluate applications with G1 and switch to G1 under Java 8 now?
• Can we expect updates to the G1 in Java 8 patch releases, so it is on the same level as in Java 9 (when this is possible)?
• or is it better to wait for Java 9 since the behavior will be different?