Once the initial excitement fades, a lot of owners settle into using the M12 Fuel line for most day-to-day tasks and only pull out the M18 Fuel tools when a job calls for more torque or run time, like framing, heavy driving, or continuous use. The M18's extra weight and size become something owners work around rather than something they mind, because they know it's there when a job needs it.
For owners in trades like electrical or low voltage work, the M18 becomes the default rather than the backup, since lighter tools weren't cutting it on their crews. The adjustment seems to be less about the tools disappointing anyone and more about figuring out, over time, which jobs actually need the M18's extra power versus which ones don't.