Haven't had any real issue with any version of this, so filing a req for the newest version is sort of arbitrary as they could very well all be stabilised as far as I'm concerned.
amd64: pass
+ 05 Nov 2013; Tony Vroon <chainsaw@gentoo.org> syntastic-3.1.0.ebuild: + Marked stable on AMD64 based on arch testing by Elijah "Armageddon" El + Lazkani in bug #481884.
x86 stable. Last arch, closing.