I have been using AGM batteries the past few years, mostly Odyssey, and have had very good experience with them. They have much better cranking capacity than conventional lead acid batteries and they hold their charge very well. On the R1100 oilheads, where the ABS start-up routine was sensitive to battery voltage, the Odyssey eliminated the ABS warning light issue completely.
One important consideration, however, is to make sure your bike and your charger provide the correct voltage to maintain an AGM battery. If your bike doesn’t charge at or near 14.7 volts your battery will lose capacity over time and will probably have a shorter life.
A little background: AGM batteries need to be charged at 14.7 volts to maintain their capacity, whereas older bikes and many chargers charge at only 14 amps. I never had a problem with this and my older (pre-2005) BMWs until my ’04 R1150GSA had a cold starting problem and I came across this thread by “roger 04 rt”. who had the same problem. His bike (and mine) were using AGM batteries but were difficult to start when cold. It turns out the bikes were charging only at 14 volts, as were the chargers, which meant the batteries were never getting fully charged. As a result, the voltage dropped too low during starting and the voltage sensitive fuel injectors weren’t providing enough fuel for cold starts. I bought an Odyssey charger and with the battery now fully charged the bike starts just fine.
You can find out what kind of battery your bike is designed for by checking the fiche and seeing what BMW sells for it. I believe Lauren has a late model R1200R so an AGM battery would be the best choice. If your bike is a 2004 or older it almost certainly wasn’t designed to maintain an AGM battery. Bikes that came with Gel batteries may not charge at sufficient voltage to maintain an AGM battery. Next time I replace the battery in my ’04 GS I’ll probably put in a conventional battery. Same for my ’04 K1200GT. But my ’12 R1200R and ’15 F700GS are designed for AGM batteries and that’s what they’ll get.