I have been trying to find out the pros and cons of each. Is there one obvious choice that is better than the other, or in the end does it not matter? Camera being DVX100, field recorder Zoom H4 or Fostex FR-2LE, and mic Rode NTG1.
I've used a Rode NTG-2 connected to both the DVX100a and the Zoom H4, with great results. When using the H4, I do usually have to boost the audio level in post, but this is not a big deal.
I don't know that there's only one best choice. It depends on the needs of your shoot.
Connecting directly to the camera simplifies editing. No need to synch up the sound in post. But it limits where your boom operator can be, and also restricts freedom of movement of both the camera and boom.
Running the mic through the H4 allows your boom operator complete autonomy, and lets your cameraman move at will. But you will have to boost the audio level in post, then synch the sound to the video. This is not hard by any means, but it is an extra step or two.
One distinct advantage of connecting the mic to the H4 is in the area of monitoring. If your DVX100 is shooting 24p, then there is a distracting lag between the dialogue as spoken and what is heard in the connected headphones. Connecting headphones to the Zoom H4 eliminates this problem.
Comparing a Recorder versus Direct to Camera, they each provide you with a different type of convenience.
The sync issues have already been mentioned regarding Recorders. It's just a little extra effort. It can be managed. The pain and complexity increases with shorter clips (and increasing numbers of them).
Let's consider a couple of examples ...
Say you're filming a stage performance, and they aren't using a PA system. You can put a recorder close to the stage to get great audio while you're filming from the back of the auditorium. As a performance, it's a relatively long recording, so the sync issues are fairly easy to deal with. If you were going Direct to Camera, then you would have to have a long cable to the front of the auditorium. So, the Recorder gives you the convenience of recording remotely and still getting great sound.
Of course, if they were using a PA system in the auditorium, you could take the feed Direct to Camera.
Let's consider the case where you are doing indoor/outdoor booming of scenes. There's a convenience in not having to run a cable back to the camcorder if you use a Recorder.
But, there's another convenience with going Direct to Camcorder that many forget to consider. Going back and reviewing the take in the camcorder with the audio, and doing it right there on location, gives you a lot more confidence that you successfully captured the scene and it's "in the can". Trying to review the scene simultaneously (or separately) with a camcorder and recorder doesn't give you that confidence. It's harder to experience the full impact of what you've just captured that way. You won't get that experience until you're in post.
For me, I would have to have a LOT of trust that my boom op really knows what they're doing to use a separate recorder. They have to be really skilled at booming without adding handling noise, and splitting the distance between actors. I mean, this needs to be done regardless. But, if it I can't review it all together right there on location, then I really need to have a LOT of trust in their skills. I feel that using a separate Recorder like this is more typical of when you have a dedicated professional audio person in your production flow.
When you're doing voice over work in studio, it doesn't make sense to do that with a camera. A Recorder (or computer) is more convenient.
Also, if you ever have to do any run-n-gun (where you don't have a choice and have to mount the shotgun to the camera), then going Direct to Camera is obvious.
The DVX can provide very good audio using direct input with the ALC [limiters] on. The Pros, it's simple, it works and the results are very very good. The Cons, the audio is tethered to the camera and this can limit mobility of both camera & audio operations.
A dual system [camera system & audio system] using the Fostex would allow mobile audio recording but will require slating for post sych. This would provide flexibility in camera and audio placement/mobility. Dual system Pros: it allows one to employ better audio recording equipment than what the DVX is capable of. You can use expensive mixers & recorders which allow all sorts of flexibility and the highest quality available. The Cons, it's more complex and expensive top end gear is EXPENSIVE, also the audio tracks will need to be syched up in post [no big deal].
Back to the original statement; a direct line input of a mic into the DVX using proper recording levels and mic placement will give very good results.