I have the E-09 "Dakar" on the front of my GS (90/90 21") and it is a lot softer than the rear. I think it will be dead when the rear is dead as opposed to going twice as long as the rear as fronts normally do. Now this could be because I am using a narrower tire than a standard GS so running a 19" will change that I am sure... so as they say your mileage will vary.
David Marshall - Quesnel, BC, Canada
2006 BMW F650 GS / 2013 BMW G650 GS Sertao
and a bunch of 4WD Volkswagens