They're really cool mills, and the price is great, considering the accessories and the shape. *However* this is a very versatile, but advanced mill. It's also only desirable to enthusiasts of big old machine tools. Thus the price.
If all you want a mill for is to learn to slot guards and other typical knife related tasks, you're likely to end up very overwhelmed, and never using this machine.
For somebody like me, that uses a mill more for general machining or fab work than knife work, I'd be all over it, I've long wanted to add a horizontal to my arsenal as I know what they're good for (read: nothing related to making knives), but if you were in the market for a mini mill, I'd stick with that. The learning curve is much lower, you can move it around if as your shop layout evolves easily, and you won't have any special space or power requirements.
A universal of this configuration has so many adjustable parts, that you'll likely be encountering all sorts of problems with them not being perfectly aligned. Tilting head, swivel table, etc, all has to be perfectly indicated if you want to be able to make square or parallel parts, and cut a square and perpendicular slot. Not just lined up to some mark, but indicated to sub-thousand of a inch accuracy, etc.
