I have had both for months now on multiple kits and have never experienced a problem. I believe Novak's own huge Cap on the GTB helps it!
On my one LRP Sphere though I run the Spektrum Cap since the Sphere does not include it's own Cap. Furthermore, LRP didn't have it available for their customers until months after the Sphere's release and even now it's tough to track one down! I managed to finally purchase one and will install it this week for some extra peace of mind!?!