I had those clear braces in high school too, probably for about 12 - 18 mths. I continued to wear the clear plate for about 6 mths afterwards then overnight only for about 2 mths or so. I am lucky my teeth haven't shifted.
I only had my braces on the top row of teeth, although I do have one '****y' tooth on the bottom row, which is not noticable at all.

As you said, it's only for about 6 mths, so I'd say do it - you'll feel happier for it!

I had no issues with the clear braces at all - no breakages or anything. I'm glad my parents paid the extra for them - as we all know high school can be a bad place to 'not fit in' .