First of all, greetings and welcome to the forum!
The ipf app and Safari are two completely different things. As far as I know, no one has had a problem posting with the ipf app.
With the Safari that is supplied with the iPad, there are definitely some issues which is why a lot of people buy (for a whopping 99¢) the Atomic browser. This browser gives you the ability to make web sites think you are using a different browser! I have mine set for the Mobile Safari iPad version (which is apparently different than the Safari that comes with the iPad) and I can post to forums with no problems.