I have 8 GTB's (all orginal NONE LiPo ) and untill last winter all were working perfectly.
I had only 2 of them die (due to connecting the power backwards) on me after 6 long years of running.
Still to this day I think the GTB is the best for Spec racing.
I run Tekin & LRP for boosted 13.5 and mod.
For 1/8 scale I still prefer Castle Creations MMM over the Tekin RS8.
I have no idea about 1S classes YET

Just my $.02