All of the three in one machines out there like at Grizzly and HF are actually older models that originated with Shoptask. And on most of them, the mill sits so close to the lathe head that you often have to remove the lathe chuck to use the mill!
I bought my Shoptask lathe/mill in 1997 and love it! For a few years the company even asked to have potential customers come look at mine before buying. I didn't mind, so I said sure. All of them wound up as customers and one guy bought one for himself and another for his son. He was a retired Navy Master Chief MR. I really enjoyed talking to him! He showed me things that machine was capable of that I didn't even know about. I figured if he liked it, it must be a good machine. I was still a hobbyist at the time and hadn't had formal training in machine shop yet. I took care of that later when I was out of the Navy. ;-) The newest Shoptask machines are even nicer than mine. I have never had to remove the lathe chuck to use the mill either! Plenty of reach on this model.
Many of the smaller three in ones are very limited in what they can do. But Shoptask sells a very good one for the money. And I can't believe I've had mine almost nine years now! It still holds a tolerance to .001". It's done great by me for the $1800 it cost!
(Edited for spelling!)