I have lithium batteries in three of my four bikes, strictly for high initial CCAs & light weight. In a 900 lb. HD bagger, the weight factor is not nearly as important as in a 396 lb. Ducati.
Plus, lithium batteries have 1/3 the capacity as similar sized lead acid or AGM batteries, meaning they will discharge 3x quicker under a parasitic draw. Your HD has a clock and an ECU, which will drain the battery by themselves if not ridden or on a tender - parasitic draw. Also, lithium batteries do not like cold weather, and if they get to a certain level of discharge, they are ruined. My advice is to stick with an AGM battery in your RG. Big Crank by Deka/East Penn through Battery Mart is the exact, same battery as OEM without the HD logos. About $100 delivered.
John, Medina, TN - 2003 Honda ST1300 ABS, 2011 Kawasaki KLR 650, 2012 Ducati Monster 1100 EVO
2017 HD Road Glide Special