Your knots will not be affected by any mechanical cutter ... they cut the hair from the tips and will not get near your base [ hopefully !! ] ..... I`m not sure what the results are/will be with one of these, on a system ..... I did see a post by a person recently on this forum, who is a men`s stylist --can`t remember who it was now..... but I think he recommended going to a stylist rather than doing a cut-in using one of these, as it can be tricky to get the layer-in onto the growing hair accurate, and is best to have it done by hand by a trained stylist. Here`s a comparison chart between a few different ones......
http://www.robocut.com/compare.html?gcli...4Qod6nsdHQ
Not sure if I`d chance it with my first system....certainly if you had 2 or 3 new systems to hand, and had one styled by a professional, you could `chance ` doing one at home with the cutter ...if you made a complete hames of it, at least you`d still have the `good`one to wear... you`ll be out of pocket by the cost of the system, but that`s something you`d live with.