Cake is much softer than FTP or PS. Poker Tracker or Holdem Manager won't capture Hand Histories of the players you play against at Cake, just your own hand histories.
The issue with all the sites currently allowing US players to play is trying to withdraw the money at a later date, it may get "frozen".
I'm Canadian so it hasn't had any impacts to the main site I play at since it never allowed US players to play there for the past 6 years. I don't have alot of money at the sites that did allowed US players to play at (~$100) so if they end up bankup I may be out ~$100.