My experience with AGM's is similar to Landyacht's, AGM's love a brisk charge. How that factors into longevity remains for me to find out.
I have some Enersys Pure Lead AGM's and there was a long operator's manual that has since, been replaced with one more succinct. The long version showed a "no maximum" charge rate could be endured by the batteries (as long as temperature was monitored, lead does melt). The kinds of testing that was done with the Enersys line makes me a believer that AGM batteries are a lot more forgiving and durable than folks give them credit.