I looked at flipping the back sprocket as well as the front, but there is a slight offset in the back sprocket, so I didn't do it. The back sprocket is slightly thicker on the (original) outer side, but flush on the (original) inner side.
I always flip or change the front sprocket about every oil change. (Front sprockets are only $19 and are very quick and easy to swap out. Front sprockets should also wear out about 3 times faster than the rear sprockets, i.e. according to the gear ratios.) My chain and rear sprocket look like new, but then I only have 18,000 miles on them.
