Yes, my Schumacher SC1281 charger shows both the battery voltage and the percent of battery charge, alternating the display between the two as it charges the battery. The AGM I replaced never got above 87% on it's own. I assume that while not a "true" deep cycle I've read that they are "sorta like" a deep cycle, so may not fully charge to 100% while driving.

After replacing and charging the battery the '06 roadster still wouldn't start. I figured I just wasted $200. I ran a couple of errands in my '07 coupe and came home to eat a couple of hot dogs. Went outside and whadoyano, the '06 roadster started. Most dash lights went out except for brake wear and BAS/ESP. After a minute or so those lights also went out. The brake pedal was back to normal. However, the spoiler switch continued to blink and would not operate the spoiler. I took it for a ride around the block and parked again in my drive way. I was afraid to turn the car off but did so anyway. I figured it wouldn't start again, but voila...it did. This time the spoiler light was off and I lowered the spoiler. I went for another short drive, parked in the drive way and shut the car off. shjt howdy it started again. I shut it off and will see tomorrow if it starts ok. It's almost like after replacing the battery it took the car a while to figure out it had a new one. Silly, but that's how it seems. In any event I'll check all of the grounds and the main engine ground under the car. Corrosion seems to be a common problem there. If so I'll just replace it with a new one. They're just a few bucks. There's a good Youtube tutorial on how to replace the engine ground cable here during the last half of a great short XF electrical video:
UPDATE: Just went out again a few hours later with that dread feeling in the pit of my stomach. Happy to report that it started right up, and did so the next few times in a row. Got my fingers crossed and guardedly optimistic because...once bit, twice shy. When I go to the store and shut it off I'm gonna have that dread feeling...at least for a while. Thanks for the support guys, and I'll do that ground mod for the battery terminal cable.