As Secondbrooks explained, you can slide the selector with the tips of your fingers while keeping the hand on the pistol grip. No effort, nor requirement of bigger hands. I assure you, my hands are quite the ordinary size The selector isn't that stiff and hardly requires any force to move from one position to another.
And of the mag change, I hardly see if there's any effect on the overall performance of the soldier if it takes 1.8 or 2.2 seconds for an untrained recruit to change his magazine, as I think we can assume every soldier in the world recieves at least some training on switching the magazine on his personal weapon.
Sure, but the more moving parts you put in to an equation, the more chance of an error there is. Basic logic and AK-family has less.
Of course, I didn't mean I wouldn't fire if the position was already compromised. The weapon is well effective on the longer distances but I doubt, with iron sights, the ability of an ordinary rifleman to put the bullet on the target accurately over a few hundred metres. Thus, opening fire with distances more than some 100-150 metres, I'd call tactically stupid. Depends on the terrain of course... It's different on the desert than in thick woodlands.
And if continuing the accuracy discussion, the RK-family uses the same basic type of a rear sight as the AR:
AR15: http://upload.wikimedia.org/wikipedia/commons/c/c2/AR15_Sight_Picture.jpg
RK62: http://upload.wikimedia.org/wikipedia/commons/f/f7/RK_62_MILES_2002.JPG
which differs from the standard open sights -style, which AK-47 uses, although the RK-62 rear sights can be overturned to reveal similar type of sights as the standard AK-family.
Now, the AR-style is definately more accurate on basic fireing range practise shootings, no queston about it. But I feel, and I've heard others state the same, that on a quick combat situation, like CQ and urban warfare, the open style is actually preferable. Main reason being that, although AR-style is more accurate, the AK-style is quicker: quicker to bring about on the target and quicker to reacquire the target after the shot, for it gives more view on the surroundings. And in the close distances of urban warfare you don't need the extra accuracy of the AR-style sights, but you sure do need the extra speed that the open rear sights gives, which makes them more preferable.
And we're talking of the iron sights now, I do know reflex sights address the issue.