One reason to stay with the 3 phase via a converter and X-mer is that it is an easy solution. When I got my first lathe, I hard wired the converter to a breaker and the lathe straight to the converter (ran that way for about 5 years). When I got a 2nd, 3rd 3 phase machine, then I got a 3P panel and set up a little distribution system. With a phase converter you don’t need to touch the original electrics (Schaublin has a good name, they probably did a good job of it - quality kit, well selected, competent assembly). Obviously you can mod it out any way you like - but with a phase converter you would be running in about an hour, and everything will work as per original. If you choose to make a rotary converter, it will take longer but can be very inexpensive - (they look pretty simple, many plans online). Used X-mers are pretty common (my 240/575 6.5kVa box was $100) - still a very easy solution. And then when you get more machines, they will be very easy to connect.