4-6hours max. con... no warning when battery dies. i would buy 2 not the extended battery. i plan to buy the 3450i next.
correct, you won't see the warning on the grace because the tekkeon's hold their quoted charge till the end instead of a steady decrease like some other batteries, but if you hold the battery up to your head, you'll hear it beep periodically (it's like once every 2 seconds or something). Second, the mah rating that is
published on the website is correct based on my tests with the 3450i, but the little lights that light up when you press on the battery are not. As best I can tell, I have a half-full battery when 1 of the 8 lights goes off, and it's a rapid decent after that. Any more then 3 lights off and I'd switch batteries.
Last, why not get the extended battery? I guess if you need 2 batteries (1 for the recorder and 1 for the amp), then that makes sense, otherwise the extender is cheaper. Have you had problems with it?