I'm seeing 12.6V across the battery terminals at idle. With some RPM the reading jumps to ~14V. Is this normal behavior?
I'll just note for what it's worth that I have run an AGM battery for two seasons and the battery seems healthy!
Thats normal. The alternator doesnt spin fast enough at idle to reach charging voltage.
Aigram,
What is your idle RPM?
Are all the battery connections shiny-bright where they make cable contact?
The far end of the battery (negative) cable can be corroded where it connects to the bike, too.
Still, that behavior does not sound bad.