I can tell you what I have seen of these in the Harbor Freight store here.
They may be okay for a home machinist (doing stuff that takes a bit more accuracy than the eye), but I don't know how much mileage you will get from them from your intended purpose. The ways are a bit sloppy, and I doubt the adjustment there is great either. The quills and gears are kind of sloppy as well, but may be sufficient for your purpose.
If it were me, and this is simply me, I would take this as a learning opprtunity and learn something that will serve you well for some of your knifemaking, and maybe more (I am not discrediting your work at all). Go to lindsaybks.com and look at the Gingery machine shop from scrap series. The books are cheap, and the stuff to make the equipment in the books even cheaper.
I am in the process of building most of the equipment in the books for use in motorcycle parts fabrication, and have thought that some of this may be useful to a large degree int he knife shop as well.
Lindsay also has a few books left on blacksmithing, as well as a very low cost propane forge and furnace. I am not trying to sell you on these folks, but I have been impressed with what I have bought from them.
If you do choose to do the 3 in 1 machine I would look at a smithy. The quality is much better.
Doc