Probably not a huge issue with a stock-ish 6.4L, the 8HP70 is rated for 700 Nm (516 lb-ft) of torque. The Hellcat is already knocking on the door of the 8HP90's 900 Nm (664 lb-ft) rating, so if there's guys running 1000 hp pullied Helcats with no TM they're playing with fire in my opinion.
I'm not saying you should go out and disable all your TM right now, just that you shouldn't look at these as "8HP horror stories" and label them as unreliable.