Well, I didn't figure we'd actually have to learn how to use it at the same time we needed to use it, or else we'd be in for a mighty surprise I imagine.Simple is a must if I'm going to have to learn how to use this weapon while getting shot at.
The blasters have a kick you need to get used to, and imagine your surprise when you fire at an enemy less then 10 feet away and that's when you realize your Phaser's on setting 16...
And as for your other arguments:
Then if you like the idea of being able to shoot it one-handed, why not pick the Type-II.The IIIa has more and better features and a bigger power cell, AFAIK. Maybe bigger top settings, too, and if I'm definitely getting shot at, I'm not going to worry about whether or not my gun could be concealed if I stick it back in the holster. If I can assume that I'm trained in the use of the weapon I pick, the IIIa is a shoo-in. It's even light enough to use one-handed in a pinch.
The Type-IIIa may be light for a rifle, but it's still heavier then the Type-II.
And it's still more unwieldy, being a rifle and all.
As for heavier settings, do you honestly need anything greater then levle 16? :)