You should get it and try it before you start planning modifications. Then if or when the flaws develop you can work on fixing and improving the gun.
Many folks recommend the Treso aftermarket nipples but many people don't have a need for them because the factory nipples work very well and the Remington #10's generally fit them perfectly, which can't always be said for the Tresos.
Springs can be changed but that may not be necessary either.
I would say only if your trigger is rough then that can be worked on, or if there's rubbing of the action parts. For example stoning the opening in the frame where the bolt comes through may rub, or fitting the bolt so that it fits into the cylinder slots better.
To be concerned about minor fitting issues without giving consideration to whether the pistol will shoot to point of aim or not always leads me to wonder why more folks don't consider the target model with adjustable sights. In that respect, the first modification that I would be concerned about is whether a dovetailed front sight needs to be added to the barrel or not to allow it to be drift adjustable for better accuracy.
I don't know which Italian steel is stronger or if that makes a difference. There may be different steels used for different parts of the same gun, and the steel hardness may even vary among different batches of guns. No one besides the maufacturer could be capable of testing various steel parts among so many batches of guns. So what if people suspected that some of the blued steel is stronger or that some of it is weaker? What would that mean when your pistol is being randomly picked off the shelf having all of its potential workmanship flaws while the one next to it or over on another shelf has less flaws or none? Don't worry about the steel. Get the steel that you like the most so that you won't be as unhappy about any of it's other flaws...or maybe you'd rather be more happy with it not being as flawed except only due to it being made from the inferior steel....