NGE, Sounds like your buddy has a 400S, not an E or K, My slightly modded 400E rips, yes it is heavy, and prolly wouldnt recommend the bike for a rider who is less than 200 LBS, but then again my 13 year old son fly's on it,
I ride my brother in-laws YZ 250 often, although it is noticeably lighter, I feel better and ride faster on the DRZ
I am very glad I bought a four stroke, matter a fact as soon as I sell my Harley I'm gonna buy my son a WRF250, it's already starting to be a problem keeping him off mine,