La 'spalla camicia' (or, if you will, the Neapolitan or shirt-sleevehead) is suitable for all body types. I am powerfully built, with broad shoulders and I, personally, find it : (a) more comfortable than the classic sleevehead and ; (b) more flattering, since I do not need (any more) padding. Remember that one of the main features of the spalla camicia is 'fullness' in the upper arms ; the sleevehead is pushed through the armhole.
Now, is it 'suitable' for business or, shall we say, more 'serious' occasions ? Some non-Italian tailors say nay - but then, they would, wouldn't they ? A large part of the problem is that they don't know how to make it ; this is not a criticism, by the way ; the spalla camicia simply is not part of their tradition. My answer is this : if you choose a dark, good-quality fabric made-up with, say, jetted (or, 'besom') pockets, welted breast pocket, etc., - i.e., without fuss - what difference does it make ? Remember also that the sleevehead need NOT be 'ruched' (i.e., gathered) ; in this way, particularly with heavier weight fabrics, the difference will be perceptible only to the cognoscenti. I personally like it ruched, but I ask my tailor to do this by making the head very full and then gathering the excess fabric into tiny pleats. However, I should never ask anyone but a highly skilled southern Italian tailor to do this : the results can be a little d'Artagnan !