I agree with you on that but you also have to remember the name of the game is "How fast you can get the project done" The longer you take equals more fuel (so your really coming out thje same with fuel), Labor cost, More maintenance, quicker is cheaper. You just gotta figure the application. Tractor and pans is not the end all answer. Then you get into jobs with big deadlines. You start getting fined 2-3k a day and then those 631's start looking good. The company I work for now has tractor and pans and a huge 631 spread so all we gotta do is figure out which Iron is the best for that job and stick it in there. We usually use our Deere to prep for nthe 631's. Get the top soil stripped, haul roads built, and fills nice and hard and then when blow and go with our 631's and use our deere for support tractors in a sense.
I think the argument is being framed all wrong. The debate shouldn't be which system should you
always use. You use both, depending on condition. Its pretty simple, actually. If your running anything lighter than moderate rock under a few thousand feet haul, you run the pans every time. Everything else, get out the Cats. What people fail to realize is there are tons of jobs that fall into that pan category. Also, pans have evolved so much over the past 10 or 15 years, those old taboos about having a "farm implement" on a jobsite are really outdated. Companies like Deere and Cat are building a super stout bucket.
Flotation is also becoming a bigger issue as the "green movement" forces its way into construction. Being able to reclaim a mine, for example. The cat will simply compact the ground to the point where it becomes useless for agriculture or green space. There is a huge market for pans. People need to embrace this.
After all, I do consider myself a deere guy. But those C18's do sound swEEEET!