well I have dragged a lot of deer out of the woods, from a few yards to several miles over the yrs, never used any cart or sled, just a good rope and a harness
I am sure anything can be a plus in some ways, and a down in others
I personally never seen the need for any of the carts or sleds to be honest
I will admit that last few yrs I have used my ATv 99% of the time, so am sure spoiled on that now!
But I come from a long line of large tract forest hunters, in my hunting cabin, were next to about 30,000 acres of forest, and for the last 30+ yrs, we have tried a lot of things, on logging roads the carts wored best as long as like Big Holla said, ground wasn't all muddy or super soft
sleds have helped and been a night mare in areas with a lot of down timber, along with the carts too
so to be honest, most of us there just don't use any at all, some have tried the plastic rolled up sleds you tie to the deer to kinda make a sled out of, it helps in snow some, but all the strings get caught on stich and brush
best method we have at camp is a cart to the nearest road if ground allows, and we use the carts with the double wheels too, and or just a rope and a harness and the old fashon way of muscle and work, we carry radio's, and get help at times , that is the best if you ask me, help, two people work the best but ain't always an option
as for FAR back hunts, there is a reason NO one in teh west drags a deer/elk
its a ton easier to quarter and carry!
so if hunting really far back, that I think is the honest best way to get a deer out!, and quartering a deer isn't really hard either!