I've had a Delta stem extender on my bike for a while. As I've ridden more and my gut has shrunk due to diet, I've gradually moved it lower. Today I removed it altogether and went for a ride. The change in height was quite drastic and will take some getting used to but it felt as though I was able to ride faster and climb a little better. On the flats it's hard to tell because of wind, but on a climb where I've previously used the 32 out back, today I did it in 26. So I'm wondering, am I feeling this accurately?

Yes, you've lost weight. Power/kg is all that matters for climbing. There's a minor aero advantage to a lower stem, but that's it.

So the different angle of my back in relation to my legs does nothing for pedaling efficiency? Honest question.