Among the XL H1, the HD 100u, and the HVX 200, which if any camera simultaneously records a 4:2:0 HDV signal and a 4:1:1 SD signal incorporating an external device such as a Firestore with the cam? I understand several output SD signals, but aren't those composite feeds for monitoring purposes?

I've searched a lot of the forums here and can't quite nail this down. Any help is greatly appreciated.

I think none of those can do it. The only one that might be able to is the Z1/FX1, and I'm not sure whether it can do a live downconvert or if it's done upon playback.

FX1, Z1, A1U, HC1, HC3...HDV to tape or external HDV device, while using an Nnovia A2d recording the composite out of the cam. Composite is always SD.
No device I'm aware of can *record* multiple formats in the lower cost category.

I think any of the cams from any manufacturer can do it through composite to an A2D; I thought the question was specifically via firewire?

If so, I think only the Sonys do a live firewire downconvert. The camera itself can't record both, of course, so you'd record HDV internally and a downrezzed DV on the firestore.

Yes, the Sony can do live downconvert, I guess I was thinking in another mental zone. Chalk it up to pain meds. :-)
You can record firewire SD to the Nnovia or whatever, while recording HDV on tape.

Thanks much for the info!

Yes, the Sony HDV cameras definitely work for this. You have to go into the menus and set the firewire output to DV downconvert, while making sure your recording mode to tape is set to HDV. Works like a charm; just remember to reset the firewire output to HDV when you want to capture that from tape.