im like you, the tech jackets seem to run small. i had to buy an XXL, after 1 wash though cold/cold and dryer in high heat. seemed like it shrunk to fit how I like my XLs to fit.
I actually had hoped it would shrink a lil because although the XXL was obviously big than I like, it wasn't super big to what I thought XXL would be. felt more like a half size big lol, if you get what im trying to say.
so in my mind after first wash it whould be good. but thats when it shocked me and it shrunk more than i had anticipated. so its like an XL thats a bit more forming (not fitted) but def not loose xl, but just that perfect fitting to body XL fit. lol
if your afraid, just do what everyone here does, just buy it take pics, and hoard and not actually wear it and wash it.