Snowdog- I haven't done any Alpine or looked much into it to know. I would guess that an Alpine designed board would be your best option since that is what it's designed for and the XV has a different use design.
You can probably get an XV or a Flagship on sale right now for a good price if you wanted to give it a shot.
I tried + + stance on the XV and attempted to practice some lay down turns Alpine style (something I've never done before) and in that case I did have locked-in-the-turn feeling. Don't know how I'd feel on a diff board, that was the first time I was trying it.
A guy at the shop I got my boards from demo'd a Flag and was doing lay down turns on it. I don't think he demo'd an XV though.
I'd have to do some board swaps between runs to try to get an idea if I thought one felt faster. They both seem fast.
One guy I talked to said his opinion is that magnetraction made him feel like it had some drag to it compared to a non-magnetraction board. But he said he wasn't sure if it did or not, or if it was just in his mind, but that was his impression.
Sprocket- If I felt like more aggressive and articulate riding I think this is where the XV has the edge on the Flag.
For how I normally like to ride, at this time I prefer the Flagship. Little more surfy (probably from the nose rising sooner than the XV), more mellow feeling, and the bigger turns. For me it is a fun ride where I can bomb and bash, but retain an element of mellow feeling.
I haven't ridden the Flag on icy or really nasty hard pack conditions yet to know where I think it stands against the XV.
On the groomed portion of the runs back to the chair, both boards can straight line haul, the XV quicker on the cutting and tight carving.
I guess for an "Oh crap" surprise moment and required immediate evasive maneuver, the XV has the edge over the Flag.
This weekend I think I'll take the Flag and XV with me so I can do some swapping back and forth between runs.