But how long do you give them to finish this 2 hour task? Less than a week? Or is this a task you expect them to do during the interview? Some people are busy doing other things and may need a week to be able to find two hours of spare time.
If you're applying for a jobs you should probably make sure you have at least 2 hours of spare time to do an interview... Take home or not, it's an interview, and if you want the job you can find 2 hours - it's a completely reasonable amount of time for an interview to take.