I've had really good luck with them holding a charge. As long as you recharge them after you use them, they don't need a ton of recharging.
I just pulled the NOCO GB70 out of the trunk of my Duster today to fire off my '71 F100 with an FE 390 because I let it sit too long because I've got the snow plow and chains on it for winter. I don't think I've had the GB70 on the charger since LAST winter. It wasn't fully charged of course, but it still had no issues firing off that 390.