Alan - you don't need to condition AGM or Gel batteries. I have Lifeline AGMs but I replaced the Dimensions inverter/charger with a Xantrex RS2000. My Xantrex can be optioned (from the control panel ) for gel, AGM or flooded-cell.
I'm not sure if you select "sealed" batteries on the Dimensions, it won't do the conditioning cycle - might need to call them if it's not in the 'extensive' manual.
John & Alan - Even when sealed is selected, the Dimensions still does conditioning. It just does it for 4 hours instead of 6. Big Help! Maybe the new ones are different - hopefully...
Just wanted to say thanks to everyone in this discussion thread for the good information realtive to migrating to AGM batteries. It was quite useful.
A special thanks goes to tomsm for the work-around to the Dimensions conditioning cycle issue. When I get sufficiently annoyed by this procedures and/or I feel the Dimensions is getting close to the end of it's useful life then I'll probably upgrade to Xantrex.