I think it sounds great. (By the way, I'm 16 and occasionaly stalk Mumsnet to laugh at the 'Teenagers' section)
I have and would always be happy to do preparation and research type homework. It makes sense to set things like that. I enjoy doing extra reading to find out more about subjects I might even dislike.
Through the past few years, I've found homework very restricting, and not particularly helpful in my education. For example, my GCSE Maths teacher would set homework nearly every lesson and it would take hours to finish. I realise that repetition is the best way to learn maths, but the amount he gave was unnecessary. As a result, I would just do no maths work at all. It was very counter-productive.
During the run-up to GCSEs(and not a moment before, the teachers slacked off on the homework a bit. I always put the time I saved to good use doing revision, reading French books/set texts, or on internet revision sites. I would have done this(albeit with less frequency) even if there were no upcoming exams.
I think it would be a great school policy if homework was abolished/the amount lessened. People assume that all teenagers and children will hold this opinion, but it's because we have a point, not 'cuz we're lazy.
So yeah, go for it. Even if you choose not to continue this after the trial, I've always thought it would be good if the teachers had some sort of 'homework rota'. I always felt cheated when I had no homework for almost a whole week, and then six separate ones dumped on me on a Friday. There should be a limit on the amount, frequency, and when it's given in relation to other subjects.
Brilliant inside info for you there, anyway. ;D