Carrying a personal recorder is encouraged by many PA firearms owners; at least those who support open carry. The obvious advantage is evidence or discussion/training after the fact. However, there are major disadvantages.
First, legality. In my state, all parties must consent to being recorded. Since police may be recording, there is already a lessened expectation of privacy. The police can request not to be recorded and you can choose to ignore that request and you may still be taken to jail albeit improperly as a result.
Second, ease of use. If you can't get your finger on record in time to catch the racial slur, why bother? Once (or if) you declare (in a reasonable volume and you're certain the other parties have heard) that you're recording, it's likely everyone will clam up. On the other hand, this could be a reasonable defense which then could move into "Am I being detained?"
Ease of use works both ways. Let's say you do get arrested and taken back to the station. Who's to say your recording won't be "accidentally" erased. Even if you say "I don't consent to any searches." Be prepared to be told "I don't give f**k what you consent to!"
If approached by the police, don't jump to the conclusion that they are there to harass or arrest you. For example: http://forum.pafoa.org/open-carry-144/85326-my-negative-encounter-ocer-today.html
(first post only, I can't attest to the quality of the rest)
Hopefully, you've seen the videos I posted about this sort of thing before: http://gunrightsradio.com/forums2/index.php/topic,2966.0.htmlhttp://gunrightsradio.com/forums2/index.php/topic,2878.0.html
If you're looking for recommendations on what and where, I recommend the Aiptek Trio from QVC.http://www.qvc.com/qic/qvcapp.aspx/view.2/app.detail/params.CM_SCID.coll.item.E165300.desc.AIPTEK-Trio-Pen-Cam-720P-High-Def-Camcorder