Everyone's body is different, but I will say that you don't need expensive handlebars to finish the Tour Divide. Older racers with grizzled bodies finish every year on flat bars, some without even aerobars to take a break on.
The TD is an [ultra]marathon. How long can you ride on your unit before things start to hurt? And what hurts first?
Do you have aerobars? If not, I'd recommend a set of those (I like the Syntace C3, but I think they're expensive) before any other handlebar change, and begin practicing with them ASAP. Having a way to shift the weight and pressure around when you ride is a huge benefit. In the aerobars, your hands get a 100% break and your butt and back at least get the burden shifted around.
Finally, as far as ability to clear terrain with a given setup, I found that rarely matters on the GDMBR. I needed to find a setup that let me carry all my gear, ride for 16+ hours uninterrupted (most of it on wide roads), get a "good" night's "sleep" and then be able to do it again the next day. I worked on that 1-3 weekends a month in my months of training leading up to the TD, and that paid off.
Thanks for the response, it usually takes about 1 1/2 hours for any pain to happen, and when it does, it's usually in my upper back, shoulders, and elbows where the pain gets in bad.
I was planning on using aerobars to stretch out my back and get the tucked-in position that is so common on the TD.
As far as the ability to clear terrain, the Unit is my daily driver, and I want to be able to ride the trails near me with the bars I want to use, and not have to switch bars, hence the Jones bar curiosity.
It certainly doesn't help that I'm kind of indecisive...