I'm not really a video guy, but I think I know at least this much...
You'll likely achieve the highest quality results recording the audio separate from the video, i.e. mics / preamp / ADC / recorder independent of the audio track on the videocam. In parallel, you could record your audio on the videocam as you do today. But afterwards, you would replace the videocam's audio track, syncing the independently recorded audio with the video source. This likely would require additional software, learning the new software, and taking the time to do the replacement / sync for every recording.
The real question, in my mind, then: are you willing to run an audio recording completely independently of the videocam, and do the necessary post-production sync?
If so, great, even if it's a bit more complicated and more effort, and there's no limit to your options in this scenario. But if not, and you'd rather stick with audio into your videocam, that works, too -- but people need to know so they can recommend gear that will integrate directly with your videocam.