I prefer the 5.0. I had 3.0 when I got my impact. I then got a deal on some 5.0. I gave the 3.0 to a buddy. I do you use my impact a lot. Probably on some stuff that I should break out a bigger impact for so for me the bigger the battery the better.
Thanks everyone! So...piggybacking...do you trust batteries on Ebay and/or Amazon (new tools as well) or are there too many counterfeits out there to take the chance. I do a lot of photography...I won't buy OEM batteries on Ebay unless I know the entity. Are tool bats the same? Any trusted sellers you care to recommend. I'm fine with using an authorized dealer, but...who doesn't like a bargain?
I use 3.0, 4.0, and 6.0 batteries with mine. They also work well with the very demanding hatchet chainsaw, so an impact gun is a piece of cake for them.
No experience with the impact, but when using the right angle die grinder the 5.0 makes a noticeable difference in the tool’s performance compared to the 3.0 I have
Just make sure you buy from a reputable source, counterfeits show up everywhere. For an impact gun, I'd own at least one of the larger size. Just have the smaller as a backup.
BTW, love the M12 line, I don't even touch my air tools anymore.