I recently put together some trestle leg table/desk supports from them. The included, sort-of-S-shaped allen wrench worked just fine. Actually, I was impressed at how well it worked combined with its minimalist design.

I'd be cautious using a drill/power driven allen bit. The wood in my trestles is not the hardest, and I can see where too much power too quickly could damage it before one's reaction time caught up with events. If you are cautious, things should be fine. If you just set a torque limit and fire away, you could end up unhappy.

I'd like an allen wrench bit for a traditional hand-powered screwdriver. Though one of those low-power electric screwdrivers we use at my work to install rack-mount equipment into racks might work OK too (if it had an allen wrench bit).

There are handheld / hand-driven screwdrivers that have replacable... bits, I guess one would call them. I have one that switched between large and small blade and Phillips heads. Now that I check, I also have an inexpensive Husky screwdriver/bit set that was a Secret Santa gift; it has hex bits, though I haven't used them.

I'd think before using it for IKEA assembly, though. For the trestles, the screws required significant torque to penetrate. Applying that repeatedly for these not too short screw, by using one's wrists and a screwdriver grip, I imagine would quickly become tiring. A nice thing about the IKEA "throw-away" wrench is that its S shape allows one to create significant torque with a finger grip, lessening strain on / torsion of the wrist.