Pros and cons of only upgrading to stiffer rear shocks?

[YarisSedan]

So debating about getting a full set of tokikos. One of my rear shocks is showing signs of leakage and i get some mild rubbing in the rear occasionally. If i bought only rear stiffer shocks but left the front struts oem would this made the car react abnormally.

I have heard of people with adjustables stiffen the rear up on fwd cars to get better handling through corner while running the front softer.. My current suspention setup is on TRD springs. Ofcourse cost is a factor and if i change my mind to get front struts later it would probally be cheaper to just buy all 4 at once. What do you guys think?