Personally, more than the rules themselves, which are quite simple and effective, what sometimes (not always) bothers me are some Abilities. Mainly those that require a lot of calculations, like Strangler. But mostly, the more common Abilities just work well enough. It is when characters do stack lots of XPs and, therefore, can buy lots of Abilities, that some combinations lead to very powerful characters.
I wouldn't bother right now, if you are just starting with the game, as your players will rise in power in a progressive way, and you will be able to see if someone becomes overpowered or not.
In the long run, rewarding less XPs per adventure -so that having lots of Abilities at high levels becomes more difficult-, might be enough to control the overpower during a campaign.