It´s weird for me how people claim Jacksons are OP while JP4 is actually way better if you know how to use it right. Allied medium tanks struggle to even penetrate it with his 230 armour. Plus it has 800HP at vet 2. Plus it has a small target size.
Yes jp4s could be better if "used right," but a unit that is good when "used average" is better than a unit than is good when "used right".
And while the armour is good, if you are getting hit as a 60 range tank destroyer you've kinda fucked up allready. Much better to have a turret, high mobility, high damage and or high pen.