To be honest with you i wouldnt argue that decision to go rtr at all...im a seasoned rc vet and still prefer to get rtr versions...its much quicker to get started and its easier to learn with in my opinion especially for someone new....the stock servo wont last you very long...it wears out pretty fast as it just uses plastic bushings..i would do the links and servo and be done with it....get yourself a 16t motor pinion for the stock motor and have fun with it..repair or upgrade as needed from there....dont drive it like a mad man and youll be surprised at just how much you dont need to upgrade or repair.
Exactly what im thinking man. Im a feather foot crawler as it is with my rigs. The metal links, steering linkage and upgraded servo are a must as you suggested. I really just dont have the extra time or money to buy a kit along with all the necessary components. I order a 4" lift kit for my Jeep Grand Cherokee and Aussie locker I need to slap in my Dana 44, aling with getting my driveshafts and transfercase linkage all situated. I dont want to get too consumed with another hobby while im working on my DD/Dad Waggon.