For the size of the batteries the Fuji's do not do that badly. I have shot recently 2 hours worth of 2.5 minute exposures on a tracking mount and still had the battery registering as full, I then shot dark frames, bias frames, flat frames, 20 of each without changing batteries. While they do not last as long as my dslr batteries, they are half the size. For the Fuji I would consider adding the grip, I always used one with my Canon cameras, but I feel the extra size and weight for the Fuji did not make sense for me, carrying around extra batteries does not seem too arduous for me, but then that is just my opinion for all that is worth.
Battery quality also seems to matter a lot, the branded Fuji batteries seem to last longer for me, the Wasabi batteries also seem to last pretty long, but I have had two other cheapo batteries fail, so I will no longer get the cheap brands, so far Wasabi batteries seem to do well, but I am getting more Fuji branded batteries. The failure mode is rather bizarre, what happens is all of sudden when you press the shutter, the shutter stays open and the camera goes blank on the screen/viewfinder and you need to cycle the power off, wait a short time and then it will power up just fine, I have also had to remove the battery on one occasion to get it to shut down. When it powers back up the battery level show full and it will shoot one or two shots then do it again. The first time this happened to me I thought the camera had failed, I was on a trip and it was the first evening of a week long trip. In desperation I switched batteries and it functioned perfectly after panicking. The second time with that brand made me dispose of them, and stick with higher grade batteries.
Alan
