My choice is to always fit two lines up to the master cylinder. Some people dont like this idea for some reason, but the thing I really really like about it is gravity ! Those pesky little air bubbles will always go all the way up to your master cylinder and with most setups, they will self-bleed when you put the bike on the sidestand. I even go as far as taking the calipers off when bleeding new fluid, cos I get gravity working the bubbles out then too. The job is done so much faster, without paying stupid money for a contraption that is trying to push air downwards !
I learnt the trick from trials riding, where believe me, you get into situations where your brakes _have_ to be absolutely perfect, or you're on your ear literally
