Are you on the edge (your limit) of how low you can presently go on your current bike? Because 18mm is less than 3/4 of an inch. Only reason I ask is because you mentioned running a 100mm to 110mm stem on your bike with similar reach as the medium...actually if I understand the above the medium has 13mm more reach. With 22mm more reach on the Large, that puts you on a 90mm stem (similar stack and assuming you are currently running a 110mm) which IMO is too short for a road bike. If you are currently running a 100mm that puts you on a 80mm stem (Way too short for a road bike. That's MTB length).