Do you mean hitting a rail built for urban on, or a rail with the lip the same height as the start of the rail/ My first time hitting a dfd was by straddling it. I couldn't be convinced to hit one like that now, sketchy af.
IMO you're still sliding it, I don't see why it wouldn't.
Now im not the most experienced parky ever but when im trying a new rail for the first time if the lip is level or close to it i ussually stradle but if its an urban hit or even a level lip its good to do it urban style. Not really much consequence either.
I feel like straddling the rail is more moving parts which means more chances for failure. I just keep imagining catching my uphill ski’s inside edge. No bueno.