I haven't been racing my 415 much as it's getting updated. But been racing my Evo IV with no arm breakage yet. This is racing both stock and 19t in the same day (I hate running 1 car for 2 classes!) for the past couple race weekends. I've actually had no breakage of anything. And I prefer the option of running different caster up front than being set with only one caster with the old front end. So I dunno.
With my Monster I've been using 6.4 on our track. I actually accidently used my 19t gearing (5.8) on my monster this past Saturday (this is what happens when using one car for 2 classes)... The car seemed sluggish lol.....
I'll be using my 415 again possibly with the LW suspension in 19t. I'll see if I like it.