Although I've never had the desire to own one, who doesn't like the look of a Bianchi? Seriously, they've got some good looking bikes with nice history.
There will be some differences; Ultegra is a nicer group and if the Motobecane came with a cheaper crank which is common an ultegra crank can be a nicer shifting upgrade. Wheels on the Bianchi are liable to be even nicer. Ultimately the differences won't be huge but having a bike you're happy and proud to throw a leg over and ride is something that can make for a better experience. If you can afford it without breaking the bank or creating problems then why not get it.