I'm in the same boat, looking at replacing the 110 mm stem that came stock on my 58 cm Jamis Renegade Escapade with a 90 mm or less. The local bike shop owner who measured me predicted this exact change when I ordered the bike because I have longer legs (33.5" inseam as measured for bikes) and a shorter upper body than usual for my height of 5'11 and ¾". No regrets because, as shelbyfv said, the head tube would shrink if I sized down to a 56.