Hi there
I run an older Peterson mill as a hobby sawing for my own use mostly. I picked it because of the portability, low maintainence and the ability to handle BIG logs. 3 and 4 ft dia logs are pretty normal here so bandsaw mills just aren't popular.
Portablilty - Yes, you can load it on a pickup or small utility trailer and set it up anywhere you can get to. I have hauled it through swamps behind a quad bike a couple of times.
Log size - The mills really shine when you get to cut big logs. The log doesn't even have to be moved from where it lays, you can set up the mill around it if need be. You can cut small logs as well, but you loose the advantage over a bandmill and you need to give some thought to the log bunks and some sort of clamping.
Manual vs Power - The nomal swingmills are all manual operation. The actual mill operation is not hard work, you push / pull it with one hand and adjust levers and crank handles for everything else. Because the log doesn't move the hardest part is removing the boards. The top model Petersons are fully automated, they are brilliant to use, but realistically you want 2 or 3 guys to use one efficiently. When you compare the mill types you should be comparing a manual swingmill with a basic hydralic bandmill, production wise at least.
Operating Solo - Yes you can, I can set up my mill by myself around a log in 15 mins and be sawing. However you will saw about twice as fast with a helper.
Blade Maintainance - The cutters sharpen on the mill in a couple of minutes. If you hit metal etc you may be lucky and cut through it with no damage, or you could smash all the tips off (luck of the draw here). You can get a jig to retip blades yourself, or have a local saw doctor do it. The blades will need retipping occasionally anyway, just through normal wear. Either way you want a couple of spare blades if you are cutting commercially, and probably a metal detector if you are doing yard trees.
Anyway.. the mills work like they say they do, how you set up your business and get customers is up to you though
Cheers
Ian