Use the 12V's exclusively in our fabrication dept. Being a Master Glazier by trade, they work extremely well for us in the fab dept. When dealing with Aluminum Extrusions, the 12V's perform flawlessly. We use them because of the lower torque requirements needed, so screws don't strip the aluminum. We use a lot of “Self tapping” and “Type F” screws, and the 12V's are perfect. Using 20V's for fabrication is overkill. You cannot hand a 20V to an Apprentice and expect them to not strip out a screw spline, or strip the attachment screws.
Also, the lighter weight is a bonus when fabricating all day, sure, batteries don't last as long as 20V's, but when you have to run 300+ screws a day, not wearing yourself out, and not stripping a single tapped hole, changing batteries a little more often is worth their weight in Gold.
We have tried others, Rigid, Kobalt, Harbor Freights line, and none of them are in use, but, our 10+ year old 12V Dewalts still run, all day every day.
The newer models are extremely reliable, and the shorter bodies allow us to get onto places that were previously unavailable.
Highly recommended the 12V line for anyone in the trades who uses cordless drills/impacts on a daily basis, just have an extra battery or 2, your arms and shoulders will thank you at the end of a hard work week.