The best quality generally is the all intra patches, Sedna or Mysteron may work for you, but 5 minutes might be pushing it.. depends on your bitrates. Flowmotion (not all intra) is another possibility that spans on a decent SD card so no real limit on recording.. really I'd say try a bunch on for size, and see what works for you and your situation.

There are a couple fail safe no adverse effects patches that I started with, they are better than stock. 44mbps and 66mbps, if your Leary start there, then maybe Sanity or Cake, or flow motion they are more stable and span on a good card, then the intra stuff, Sedna or Mysteron, they don't span but they make great image quality.

For comparison, I have a co worker that has a 5d II, I showed him some of the footage off the GH2 with the 44mb failsafe patch and he said it was way better than his 5d. His 5d wins at stills, hands down.. but the GH2 does great video even stock or lightly tweaked.

Really it comes down to what you need, want and like. Try some out and see what works for you. Maybe bring a few along to the shoot and try some of the intra ones first.. couple dry runs with Sedna to see if it works, if not have a solid backup patch ready to go , as long as you have a full battery you can re-patch anywhere if you have them along on extra SD cards that are loaded and ready to go, don't even need a laptop with.

Have good quality SD cards.. and tested cards.. bad cards or writes will ruin your day faster than anything, and the higher the bit rate the more your odds go up of having writing issues. Bad cards/writes can cause you to loose footage.

Heck at work we have totally stock panni ENG style cameras, Had a new untested card (was probably a faulty card), We had to shoot, a one off, ideally one shot, with 130+ people as cast, flash mob style event.. popped in the brand new card (same as we always use and trust), formatted it, shot it, reviewed footage on camera after we shot it.. looked good, sent everyone home, packed up, took the camera with the card still in it back to the office, pulled the card, went directly into the computer and ...... poof gone.. corrupted data ... instant bad day.