PLenty of difference.
I've recorded a demotabe using the standard inputs, and later recorded another one using an elco cable.
Nice sounding, as they say, more headroom(!).
I would say go for the elco if you can. There is some crazy guys over the web which shows how to rewire your adat internally to make the p2 outputs +4, by using the elco internal cabling, but I think it's too much work and isn't guaranted to work.
Better stick to the clean solution and get an Elco.