The title should go as 'which P55 mobo to choose?' as you have already decided to get an i5. The mobo you chose is not bad and yes it supports SLI. What's your budget for the mobo?
I suggest this one:http://www.newegg.com/Product/Product.aspx?Item=N82E16813131621&cm_re=asus_p55-_-13-131-621-_-Product
My budget for the Mobo is: $230.