I've been doing exclusively duck the for two years (50+ times going up the mountain) and went forward stance this year (about a dozen trips). I don't want to go and outright say it's better, since many experienced riders carve excellent using duck stances, but I've found an improvement in both speed and angulation for various reasons.
1.) I liked the mechanics better, as I found forward stances were more dependent on knee drive and rolling of the ankles as opposed to when I went duck and found I really had to focus more on the "hump and dump" action which took me out of rhythm and seemed a little unnatural for me. I had a pretty extreme duck (+21,-21), so that might have something to do with it
2.) I'm able to dive forward better into my next turn. Again, I had a pretty extreme duck, so that might have something to do with it, but for some reason, my forward motion going into my next turn wasn't as fluid and lead to some pretty sloppy turn initiation. Maybe another year duck would've improved it, but with forward, I found it much easier by the second trip up the mountain to do this going down steeps or going at speed.
3.) Body alignment. With duck, your body is aligned with the board and with forward stances it seems a bit counter-rotated forward, but really, it's aligned with your feet. When riding dynamically, I much prefer having my body position face more down hill than to the side of it. Plus, I don't have as much neck pain looking to the left all the time as I did with duck. LOL
Again, not for everyone, but it might be worth a try. Also, you might not like it all that much the first time like I did. It took two trips for me to dial it in (angles, stance width, mechanics, etc.), so give it some time.