[Mightypeon]

Well, thanks for the usefull post, I am actually using more Arbalests than before this argument now.
Yet there is also the time angle to consider.
In some situations, Sappers and Arbalests may be performing exactly the same (as in f.e. doing nothing) on the tactical map. There are also situation in which an Arbalest heavy approach is a "safer" choice while sapper get stuff done quicker but with greater risk of failure.