Help understanding "moderate" arch support

Hey all!

I was hoping to get some input on some new boots. I for sure want to get a a thurman last, but I am in between the T55 and TNW. The past year I have only worn a pair of Limmers standards and Jim Green 719s. Having never worn a Nick's boot, I am uncertain how the TNW (more "moderate" arch) compares to these other lower-heeled boots. Are they similar, or is the moderate arch more support than the boots I own? Does anyone have experience and could chime in?

Essentially, I want to see if should quick-ship a TNW builder pro or a T55 builder pro.

Thanks for any help in advance!