Depends on what you need to use it for. Most people can get away with just needing the tools provided in PRO, other people needs the extra tools that EX has.
(I do seem to have this issue though where I don't realize that some of the stuff I use are EX exclusive, and I'll only figure it out when I try to explain how to do something to someone and they can't figure out what I'm talking about until it clicks they're running PRO and don't have that tool)