I spent many happy years in a University workshop with two Schaublin 53's. Originally bought in the 1960's they ran for about 12 hours each day with not much problems. We had (still have!) ALL the available kit for them. When new they cost three times (equivelent) what was paid four years ago for a brand new CNC mill with axis movements of 1500 x 800 x 800 Z.
The 53's are still in use every day and will need to be replaced eventually but with what?
We also had a Huron which was a better mill and much easier to use. The Dean Smith Grace of mills!
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With what?" is a great question, and I would suggest making it clear to whoever is making the eventual decision, that they carefully consider whether the machine being brought in as new, is not at least as worn out as a very well used and abused "Quality" machine.
We got screwed on that, in my last workplace, as they had to bid out the replacement for our Varnamo mills, and got a import piece of crap that wasn't near as well put together or capable (it eventually went back) and was nowhere near as intuitive to use, either. Push a button, lift a lever, to make it go one way, push a different button, lift same lever, to make it go the other way. Caused a fair few crashes, as all the Varnamo mills were very intuitive to use, where the direction you moved a lever, caused a very direct relation to the movement produced!
In a general sense, I would figure a Schaublin 13 would be almost the ideal home shop mill, if you could get all the goodies along with (a not minor problem). the 53 seems more aimed at the high end Pro user, and seems a lot less available on a global scale, though i is also a lot heavier built than the 13 seems to have been.