I have plenty of third party feeds in my members are and have never ran into a problem with ProxyPass or Phantom Frog in that respect. I now use ProxyPass and I am happy with them.
I used to use Phantom Frog and they were good.... too good. I ended up getting a lot of members banned. Even though they have a feature so the member can type in correct info and get back in, alot of guys never read that they just got pissed.
I have never used strong box so no opinion there.
Hope that helps.
