I read through the thread quickly and can offer some other insights. When I was working for Pacific Logging (one of the 3 owners of Forest Industries Flying Tankers [FIFT] along with MB and BCFP) I was trained and qualified to call the Mars when I was on fire duty, mostly for the Rivers Inlet operations. We also got to use any of the FIFT assets, like the Grumman Goose that was the bird dog and the helicopters, as long as it was not fire season. I have lots of seat time in the Goose.
I asked one of the pilots why a Goose as a bird dog, and this is what I was told: the pilots rotated between the two Mars and the Goose and they found that the Goose had very similar flying characteristics to the Mars. So if the Goose had trouble accessing a fire, then they knew there was not much hope for the Mars. They had issues with government bird dogs that typically were much smaller and more maneuverable so they ended up guiding the Mars into situations that required the Mars to bail out before getting to the fire. Also, the pilots of the other bird dogs did not know the capabilities of the Mars as they did not work with them on a regular basis.
There is a Mars engine at the British Columbia Aviation Museum in Sidney in case anyone wants to see one; it is a Wright “Cyclone 18” R-3350-24WA:
http://www.bcam.net/engines/ about 3/4's of the way down the page.
