Thank you, Darcy, for your in-depth critique. All your points are well-taken and I will have them firmly in mind as I begin my next saddle - very helpful.
About the custom tree thing, though... I know there is a lot of opinion about the advisability of custom-fitting trees, but I look at it this way: Most of the boots in a boot store are made to fit most of the buyers, but there are some people (like myself) who can't wear any (or very few) of the boots in a boot store - why should I be in pain trying to wear boots that most other people can wear? So I shop long and hard for boots that are comfortable (and keep them forever) - and I'm in heaven when I can afford custom boots made for me.
It's the same with the tree. Most factory trees fit most horses, and there are a few horses that most factory trees don't fit. There is considerable difference between the Bowden tree that was supposed to fit this mare and the Dittmer tree that does fit her - much more than gullet width and hand-hole. More than that, Travis sent me the tree in bare wood so I could fit it on her and make final requests - more flare in the bar tips and a little shaved off the upper front bar tips. Yes, it's micro-fitting, but why should she be uncomfortable wearing a saddle just because it fits most horses? (And I think he might be incensed at the idea that he didn't do much to fit her...). The same holds true for the tree for my next saddle - a Nikkel tree for another horse that turns out to be also out of the normal 85% of horses - we did the measurements and photos and Rod made the tree, and it seems that this horse has a 95-degree bar angle (I knew she was broad-backed, and Bowden could not get it right) and much more rock than most horses. Again, I compared both Bowden trees that were supposed to fit her with the (gorgeous, work-of-art) Nikkel tree and there is a huge difference, both side-by-side and on her. Her own tree will make a difference to her and in her performance. And since I'm the saddlemaker, why not?
I understand that in Europe there's a tradition that a horse has its own saddle and when the horse is sold, the saddle goes with the horse. No doubt they're English saddles and the stuffing conforms to the horse, but still the concept of fitting the saddle to the horse applies.
Some day when I make saddles for other people they probably will not want to go the custom tree route because it takes a LONG time and costs more, but the idea that my two mares have saddles that fit them far better than factory trees makes the whole process even more worthwhile.