The 509PLONG plate works with the "Manfrotto 577 Rapid Connect Adapter" (B&H has them). You can use the 509PLONG plate on the 501, 503, 504, and 509 heads without any issue.
Which also means you can use those shorter plates on the 509 head if you need to.
At this point I've:
- piped audio in via a MixPre (don't own the MixPre)
- piped audio and recorded "blind" via a Zoom H4n (I own the Zoom)
- piped audio and recorded "blind" via a Marantz PMD660 (I own the PMD)
- piped audio and recorded timecode synced via a Sound Devices 744T (don't own the 744T yet)
I use the Red XLR to Mini cables when working with the Sound Devices 744T to get scratch/reference audio in camera. I use Hosa cables splitting to L and R mini 1/8" when working with everything else listed there. I'm planning on purchasing a Sound Devices 744T with a mixer down the road as it's pretty much standard equipment out here in Los Angeles. For production work out here timecode is pretty much a must.
If you're curious about mics. I own and use the Sennheiser ME66 shotgun and 2x G3 Wireless Lavs. I have a few other mics I use as well mostly used for field sample and vocal work, but these are what I've used the most at this point.