In am just having this done myself (at the LBS as I know chaindevices can be fiddly and may need modifying). Mine is a 2011 five. I did consider going 2×10 but the issue of max front chainring sizes came up. As far as I understand the problem arrises only when shifting to and from the granny ring, but correct me if I am wrong.
If you run 2×10 they recommend only running upto a 32 front (but I do know some people have run bigger and it was ok). They chain can otherwise catch the weld on the pivot when chainging between the middle and the granny ring. (I presume the mech moves the chain across before it drops down).
From this I took it that as long as you run 1×10, and you do not have to change to the granny, you can just run bigger rings. I have gone for a 34t, there were issues with the chain device and the swingarm, hopefully now sorted using a file..
Anyone please correct me if I am wrong (I suppose I will find out soon enough when I pick mine up from LBS).
Simone