Prusa I3 upgrade worth it?

So I just picked up what I'm 75 is an I3 with a bear upgrade with a Mostoite Bondtech hotend that has a wire that will need resoldering. And I am wondering if it is worth it to upgrade the printer to an MK4 or MK3.9s.

I'm not able to post pictures right now, but I will post them when I'm able.