I can never quite understand the reasoning that leads people to put any old sh*te oil in an 'X' thousand pound bike You're only putting it in every 6k (or perhaps 3k if you're so inclined) - what's the saving? It's not like you're paying half price for your fuel.
Only in respect of the dry clutch meaning that you don't need to use a motorcycle specific oil without friction modifiers. You should still use an oil that meets the minimum wear specification. SG as in Act>Evo 20W-50 is a relatively low standard and has now been superceded by SH. The stuff which BMW now recommends for Ultimate Protection, ie Power1 Racing 10W-50 is to API SL spec.
they were also doing Semi Synth API SL in 2L bottles for "3 for £10", a couple of weeks ago - had to buy some just to put on the shelf, it will go in one of the cars.