Is there an advantage to having a 4-sided vs 2-sided changing pad? Right now, I'm stuck between these two:

Simmons Kids Beautysleep Naturally Contour Pad (2-sided)
http://www.amazon.com/Simmons-Kids-Beautysleep-Naturally-Contour/dp/B004MMDZVI/ref=sr_1_90?s=baby-products&ie=UTF8&qid=1340021542&sr=1-90&keywords=changing+pad

Naturepedic Organic Cotton Contoured Changing Pad (4-sided)
http://www.amazon.com/Naturepedic-Organic-Cotton-Contoured-Changing/dp/B001AV40Z4/ref=pd_cp_ba_3

The Simmons, while not cheap, is half the price of the Naturepedic. Both are Greenguard certified, which is the important factor. Thoughts?