Correct, although I wouldn't do 4.55 i'd start with 4.05 since it's lower and you can probably do a bit more. If 4.55 is better then you can always upgrade but you can't downgrade
Just to confrim before i buy, if i got the PS4 Pro with 3.70 i can upgrade manually to 4.05 then apply the hacks? in short PS4 pro with 3.70 are hackable?