Page 138. Engine type. 2 overhead cam shafts. = Twin cam. No?

The manual states 20w50 for your bike, but also lists 10w40 as permissable. The BMW/Castrol chart states 20w50 for boxer engines. If it was my £4000 bike I know what I would use, however as Chris pointed out earlier it's a boxer so it'd probably run OK with olive oil in it!! 
I'm just trying to be helpful. That's all. The irony here is that you're usually the first to jump down someones throat if they suggest a cheap bodge on their £500 Omega and regularly lecture folk on the importance of using correct parts, oils and fluids.... 
In answer to your original question. It'll make little difference when you change the oil! 
BTW what did Opie recommend? 
2010 introduced a later engine, known as 'twin cam' (well that is what all the press said) which was a tweaked engine compared to mine, it felt very different to ride engine. wise. So you would rather I go by a chart that is very general, than the hand book I got with the bike?

Appreciate the advice, but it's no bodge. I've been researching it for some time across a number of forums from peoples actual experience. As said earlier, the oil specs change over the years as certain ones are discontinued/improved. As BMW use Castrol, if they decide to drop type, they have to change the recommendation.
When I called BMW today and stated 20w50, they said they now are told to specify 15w50! But he stated the air cooled boxer ran quite happily on 10w40, when launched they specified that. It's only as technology has moved on, they specify different oils.
Also manufactures specify a lot of things, Vauxhall suggest 20k oil change intervals amoungst other things, WIM have a custom geo setup, outside Vx spec. Do we always do what Manufactures specify?
So it's no bodge to use it

So far I've had people vote for two of the 3 options, drop it or ride it. With MarksDTM suggesting it is worth dropping it early due to moisture, I bow to his knowledge on that. So does make a difference.
Not asked Opie oils as I'm not really interested in what they say.

At the end of the day its Boxer engine as Chris says & I rarely rev it about 6k rpm... so it's not exactly pushed!