It's a very personal thing. Mid-kneecap is fine. I like the kilt to fall at toward the top of the kneecap. Something to keep in mind with the traditional, however, is that it can be place an inch or two above the navel (I think it's best above the navel). If you haven't, try wearing it slightly higher before trying to change the kilt. Wearing it a little higher is perfectly acceptable. I personally don't understand the aversion that men who are new to the kilt have to the high length of the traditional. I know we wear pants lower, but the traditional kilt is just that... traditional. It doesn't (thankfully!) change with the fashions.