I think you’ll find the DVX100a has better low-light performance than the HDV Sony you mention, or any other HDV prosumer camera. If you had a choice of the Sony PD-150 or pd-170 or the consumer version of those cameras, dcr-vx2100, these would probably give you even better low-light performance. All of these, of course, are SD, not HDV cameras. For the moment, low-light takes a hit in HDV. However, to compensate somewhat, if you boost the gain +3 or even +6, the HDV cameras remain surprisingly low-noise.
But if you are distributing your video via DVD, you are forced back to SD (for the moment) and so there is no advantage in shooting HDV, or so it seems to me.
In your place, I’d shoot with the DVX100a, which is a terrific camera. Further, you are apparently quite familiar with the DVX100a, which will free you up to concentrate on covering your wedding. A far more difficult issue will be, I suspect, getting good audio. If you cannot use radio lavs or planted mics, get a good short shotgun to help your efforts. From reliable reports I hear that the Rode NTG-1 is terrific for the price, under $250. After that you are at $500 and up. (https://tinyurl.com/yrh8y3)
Rick
Rick Wise
director of photography
Oakland, CA
http://www.RickWiseDP.com
email: Rick@RickWiseDP.com