I've always used a lot of drop, but around age 55, I decided to try increasing my drop from 9cm to 11cm, all at once. I changed from an 84 degree stem to a 73, since I had no spacers to remove. Didn't take long at all to get used to it.

Increasing my reach is another story. With a short torso, I use about all the reach I can tolerate, to maintain knee to arm clearance, when pedaling with hands in the hooks. Even a 5mm increase in reach can bring on some discomfort in the shoulder area.