That's a pretty scary bug. Who knows how stuff like that will trash your data if you aren't properly checksumming everything.
CMS and other GCs have the advantage of years of bug-squashing and tuning. G1 is exciting, but I wouldn't personally use it on anything important for quite some time.
Of course, that's a totally unfair comparison: CMS has had a decade of bug squashing...I'm sure it had equally scary bugs when it was new. But that's the point. Don't use new, shiny GC's because they are still squishing bugs :)
(Sorry, preaching to the choir, I just get frustrated by everyone claiming G1 will solve all their problems without investigating potential downsides)
G1 addresses certain problem areas of CMS and replaces them with others. Honestly I hope in ten years from now we have better choices in HotSpot than CMS or G1 but right now it doesn't look like it (if you don't count Shenandoah with has other issues).
Having that said I have recently seen G1 performing exceptionally well in production: 120ms GC pauses with a 120 MB/s sustained allocation rate with basically default settings (apart from GC logging).