Regarding small people like us with negatively inverted stem ... i.e. 25 degrees.... that seems too negative of a slope, would it change the handling dramatically?

What does the angle have to do with it? The stem is just a vehicle to affix bars to a fork.

I'm 164cm and ride a Ritchey P29er in 15" with a rigid fork. No problem with position or handling, although I will likely look to fit a negative rise stem at some point. Only on the really twisty singletrack do you notice the downside of the handling, but on anything where you can get the speed-up the bigger wheels really roll. Depends on whether you want a bike for long days in the saddle or for playing in the woods?

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Did you post pics of the bike on the forum?