AFAIK the A1 is a CCD camcorder which means you won't have rolling shutter-issues which can be an advantage, if you're about to use faster pans or if you're shooting fast-moving objects like ... uhm ... cars ;)
I personally find that with "real" camcorders you can work faster than with DSLRs, but that's maybe just me.
Audio - like Steve wrote - will be better than with a DSLR if you plan not to use an external recorder.
Without a tripod (or other stabilizers) you'll get more stable pictures with a bigger camcorder, which can be an advantage if you want to shoot with a moving camera and don't have a dolly, a slider or a steadycam.
If you want that DSLR-Look (DOF etc)... well, forget the HDV camcorder...
We shot a commercial for a car dealer (plus repair-shop) last year and we used a 7D, a T2i, a GoPro and a Sony HDV-cam. Used the Sony for the interviews (audio from a lav-mic directly into the camcorder --> no fussing around with sync in post). For the driving-scenes we used the GoPro, for all other scenes the 7D and T2i.
Especially in the repair-shop (which was dark and narrow) the small size of the DSLRs and the speed of the lenses we had were of big advantage. You can shoot things, that with a bigger camcorder would have not been possible.
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