The motor brake means that when you let go of the trigger, the chuck stops dead. This helps if you're, say, installing a wood screw and need to stop when it's flush, rather than stopping at a certain torque. The inertia of the chuck won't cause the screw to go a smidge too far.
The RA drivers are good for tight spaces. For most electronics work, you're not limited in space. So being stuck with 585 RPM is a compromise.
I use something like this:
http://www.amazon.com/gp/product/B003BEE2LU?psc=1&redirect=true&ref_=ox_sc_act_title_1&smid=ATVPDKIKX0DER1300 RPM for zipping out screws. Clutch adjusts far enough down for insertion on most electronics work. Real one-handed, single-sleeve chuck takes 4mm or 6mm driver bits, or drill bits, with no play. You can even chuck up a small jeweler's screwdriver. And it has enough torque to drill big holes and turn deck screws to boot. It has a slip clutch and motor brake, and you can torque the screw manually if you let go the trigger. The runout is so low, it's good enough to use as a mini lathe.
For the tiny little cell phone screws, you're probably faster with a small-barrel manual screwdriver that spins easy with a twist over any powered tool, simply for the ergos. Getting the screw in the hole is the hardest part, there. In theory, the motor brake would help by allowing you to zip the screw in at high RPM and then stop short to finish manually. But in practice, any screw that needs that little torque where the clutch limit and/or inertia comes into play is going to be so short that you don't need a power tool, unless doing hundreds. For a specific project like that, you might want one of those fancy mains screwdrivers with the feather clutch; they come in flavors with 1000+ rpm with a clutch that adjusts down to nothing. Set up your assembly line, hang the driver on a stand, and get to work. For repair/prototyping with these tiny screws, this is where those cheapie little AAA battery deals can be handy, despite being slow. The umpteenth time you uncrew/rescrew the chassis to tweak things, you don't care how slow it is. You're taking a mental break, anyway.
A couple of months ago I bought the little Worx WX252 cordless driver here
I have one of those, too. The bit changer works great. The battery is ok. But it's like a Dremel driver. It's slowww. And no clutch. It doesn't need one, because it's so slowww.