I agree with Jock and Steve here. Wearing a kilt on the street here in Scotland midweek I have often been taken for an American tourist.
The kilt is neither the most comfortable or practical garment for many activities.
For casual wear during warm summer weather I have found the Utility kilt style with pockets and no sporran is a comfortable alternative to shorts, yet non-trad kilts haven't caught on as mainstream wear here in Scotland where there is still an assumption that kilts should be tartan and are only for more formal occasions or for following the national soccer and rugby teams.