This cordless screwdriver from Milwaukee compares similarly and favorably with the Hitachi DB3DL. If you've read the Hitachi review and just want the short comparison, the Milwaukee offering has slightly less torque, but twice the battery capacity. The higher battery capacity makes the Milwaukee weigh slightly more. And the Milwaukee costs a little more. Other than that the two drills are very similar. This is a stick driver with a hinge in the middle. It's compact, lightweight and versatile. You'll mostly use it for assembling, but you can also do very light driving.
I have the same singular complaint for this drill. It's not variable speed. It does have 2 speeds: 200 and 600 rpms, but you can't ease down on the trigger to get the drill to rotate just a little. It's either 0 rpm or 200 rpm. Two hundred rpm is slow enough that it's not a major problem. You'll be able to work around the lack of this feature. But I still call this a minor complaint.
The Milwaukee screwdriver has a 21 position clutch which I don't think you'll use very much because of the limited torque. But it's another feature that might be important to you and it doesn't add much to the cost or weight of the drill. Like the Hitachi this drill has been around for a while and it has enough reviews on Amazon (and good ones at that) for me to know it's working for a lot of people and that it's lasting a good while.