To run a decent powered chainsaw all day on fuel and oil works out quite expensive, very noisy and I find it uncomfortable after a couple of hours. You've got the issue of small timber snatching on the chain too. Along with all the stops you have to make to refuel so often and sharpening/chain wear it can be a pain.
With a bench you can run all day on a tank of red, which in my little Kubota costs about £3 as it's only 600cc - 12.5hp. No fuss, just pick up a log and run it through. The timber loss to sawdust if you do a lot is greatly reduced and the blades stay sharp for months not hours. Add to that the relatively short life span of a high revving two stroke engine and the bench comes out a winner every time. A mog would run one easily just ticking over so it's quiet in comparison.
If you get a chance to watch one running or use one try it. You'll be pleasantly surprised by their simplicity I think. Here's a video of the one I've bought working...
https://www.youtube.com/watch?v=00-y8f-SAXI&list=UUdwsN1hLj5Sif_sePfmnI-g&index=10