This 100mm is for sure not a general purpose lens.
But its very strong in its specialities which are macros and close-up portraits. For portraits, its a bit extra sharp which can be easily fixed in LR or ACR.
50mm and 60mm macros would be tough for insects as the working distance is very less. 100mm gives a breather for such distance and is reasonably far to take good macro shots at 1:1
So far, this is the best lens under $1,000 that i have seen effectively using full frame of the photo at f2.8.
Carrying a 50mm f1.8 should not be a problem at all as its the tiniest of the lenses 