Are sidegrades really gonna be balanced?

[Dreamcast]

I like the theory of sidegrades, they sound balanced(give up something to gain something) but will they actually be balanced in reality?

I mean from what I understand if a gun gets more damage then it losses accuracy or vice versa which means it will be balanced....and it basically will just be done to suit somebodies gameplay style.

But the more I think about it...The more I think one of the sidegrades is going to have an edge which will not make it balanced and thus everybody is gonna use that sidegrade.