In reply to scorpia97:
> Has any one tried combining a genesis and serenity for regular use as doubles?
Yes, I've got exactly that combo and have used them together many times with absolutely no problems at all. I see the modern Serenity is called 8.7. The one I got was called 8.9 (for this review
http://www.ukclimbing.com/gear/review.php?id=3765 ) so presumably they are even closer in size now. I've also used a Beal iceline and Beal Joker together and although they differ in size a bit more, had no problems with that either.
I sadly found my serenity has small coreshot in it recently so needs to be chopped in half. I've chopped a few metres of both ends previously, but it has had a tonne of use since 2011 so has done amazingly good service. Nice rope, although like I said in that original review, its dry treatment has always been noticeably less efficient than the Beal and Edelrid ones.