It is very slow. But it's faster than me.
I personally haven't run into a heat issue yet, but I'm definitely constantly aware that I'm probably approaching a use ceiling / failure point at some point. Strain on the truck frame, battery, alternator, parking brake, controller, winch motor.... So far I haven't broken anything, but it's only been a few months, and I assume I'll find out soon.
The hardest I've pushed it was probably 4 hours of dragging brush piles and logs up to 1000lb across flat forest floor. I haven't maxed out the pulling power completely, yet, because I don't want to break my truck. Most days its just scootching a big log or pulling a couple brush piles up a bank. Often it's a winch pull, then a pull with the trans in 4lo.
So far using the electric truck winch as a solo I've found it really helpful, and I know I'm always going to want a winch above the chipper, so I'm surprised that I haven't seen the two combined before. But there's a lot I haven't seen and a lot I'm learning, so that doesn't mean very much.