I've ridden both, and prefer tighter geometry. My bianchi track bike is great, zips and turns with zero effort. The road conversion with slacker geometry that I rode last winter was super sluggish by comparison. When I first switched I couldn't believe the difference.

Right now I'm riding another road conversion, which is a smaller frame than the track bike, so the sizing ends up being similar. The wheelbase is pretty much the same, as is the handling. I can't tell too much difference, other than it has a brake. The bianchi looks a lot better IMO. The rear wheels sit about the same dist from the seat tube - 1-1/4" on the road and 1/2-3/4" on the track. There's not much clearance on the front fork on either, though this is a lot more noticable on the track. I can't fit a piece of paper between the wheel and the fork on it...

So I guess it all depends on the frame you're converting.