For H.264 mov, transcoding is necessary because:
1. Timecode: It adds timecode which other plug-ins also promise to do. I do know that Canon is working adding timecode from metadata like GLuetools intended to. (As an aside, Canon is releasing the beta in Mar, not the the golden master.)
2. Computer power: Pro Res works well with lesser computers, like the Core2Duo of the MBP. You can do more with about 3x the size of your master file. The H.264 files are CPU intensive. At 40+ Mbps, it will drag most computers down to have to render to display multitracks etc.
My suggestion is to use MPEG Streamclip to transcode your "working .mov files". A slightly different way is to make a first cut then transcode those clips into Pro Res via Media Manager, recompressing into Pro Res. That'll be much slower than using MPEG Streamclip but you'd be ready to roll once it's done. Overnight transcoding is perfect for that.
Compressor works too but is slower. However, it does a good job of conforming 30fps to 24 or 25fps. I suggest you do that to your output file and not bother with that unless you don't know what it'll look like.
Shawn is right that Pro Res is not X-platform and thus not a delivery option. Formats like HDCAM, HDCAM SR are always accepted, except for smaller production houses.