yeah trap's damage radius does upgrade, but it hardly justifies upgrading the traps (beside sparing some DLUs), correct? damage radius can be valuable , but far less than doubling(at least) the amount of traps. traps spam is the way to go i guess.
hi i am not a true expert in minimaxing characters, but in the past, i have experienced the following statement: one upgraded tower is better than 2 non upgraded towers. this seems to remain true. however i have noticed one exception: huntress mines. on my character it is better from a dps perspective to stack level 1 mines instead of upgrading them ... can you confirm you experience similar things?