Need a new wetty for COLD

winter conditions. Think the one I have is a 5/4, should see out this winter. I wear a hoodie when its really cold, cut out ear holes because I couldn't stand getting water trapped in ears but don't fall of as much these days so keen to get another one.
What I am considering at the moment is getting a 3/2 and a 2mm vest to wear over the top when its really cold, maybe a vest with the hoodie attached.
Questions are -
Anyone layer items like this? pros/cons
Vests with hoodies attached, any good? pros/cons