Wired vs Battery Impact Wrench

Most driver bit sets come with a 1/4" square drive adapter (my small Milwaukee set also came with a 3/8" drive as well, though I don't know if that's common). With that one bit, your driver is instantly almost exactly the same as a 1/4" impact wrench. You'd have to look at torque specs to see if the models you're considering are comparable, but I bet they are. Those little impact drivers have come a long way -- battery life is great and the torque is hard to believe.

I'd only consider a square drive impact wrench for heavier automotive (or other mechanical) use, and only in a larger size like 1/2" so it can provide some real help in removing tough fasteners.

The pin/ball detent system is the more secure socket retention method. However they can be a real bear to release. They are especially tight when new sockets are used on a new gun. This is compounded if your hands are wet or greasy. The friction ring is still secure but lends itself to easier socket changes. So if you are going to install one socket and use it all day, over your head where it is likely to fall off the detent system is your choice. If you are using different sockets frequently where easy removal is important go with the ring retention.