Pipe is blowing a bit so am going to take it off and fit new gasket this weekend. Now Wemoto had 2 types of gasket so ordered one of each type.

I've always used the round profile copper one in all of my 12 years of burger riding, however they had a flatter profile aluminium one - anybody used these before, oe should I stick to the original type??

Lot of these cheap copper ones arnt solid copper just copper outer with some stuff inside .

I thought it was the “stuff inside” that conformed to the irregularities of the mating surfaces to form a better seal, hence use the once. But that’s only my limited 20 odd years’ experience as a mechanic speaking.
If the two surfaces are both clean and well machined either will work.
I would still put a thin smear of exhaust paste on the solid one though if you use it.

Just how I would do it - not saying it's right

Well, for a change I used the flatter profile aluminium one, copper one is in the toolbox. 30 trouble free miles so far