I would prefer the underseat-tank of Markus.
Less weight on the front, doesn't break the line of the MM
I did a test. Result : 365 km (227 miles) with the 2 tanks.
GSMarc from BELGIUM
2014 KTM EXC450 6Days
2008 HP2/MM ABS
2000 R1150GS (fortunately sold)
GSMarc screwed with this post 12-28-2012 at 11:28 PM