Good idea, but it's going backwards as it's just a reversal of the old hand saw.
It might be good on delicate things, but we have so many good electric machines out their why would you bother with a manual one.
I think it could get very tiring real quick and would be of no use for anybody that has a bad back or arms etc.
It's just like those adds on TV where they make it look so easy, but when you get it home and try it yourself it ends up in the back of the cupboard or the bin.
As for a "saw that can be used while the family sleeps" I think the sound of the carriage on the guides woulds make an annoying sound and even more when it wears in, the wife would not be happy.

Dave