X3 accurracy and repeatability

[firebrick43]

Hello,
A friend and I are planning to start a small machine shop on the side and will be purchasing an some used CNC equipment (Bridgeport boss) to start with. Since I am the one that is good with electronics and mechanics I will be doing the retro of a new controller/drives. I am leaning towards purchasing a small mini mill to cut my teeth on.

I have been to the Sherline factory and really like their products, but would like a little more heft to handle steel.

So my question is how accurate are those who have x3 converted to cnc w/ballscrews?

Will I reach Sherline's level of accuracy?

Is the ways/column/table square or able to be scraped/shimmed/adjusted square?

I ask because I have read many threads of those that have converted but there is hardly any mention of the final results. This will be a learning project for cnc and a hobby mill to do mostly Sherline sized work but hopefully with enough rigidity for an occasional project in steel. I am a machinist by trade and have medium sized equipment in my shop but would like a miniature mill and lathe for some model making.

Has anyone used http://www.cncfusion.com/smallmill1.html "Small-Mill Deluxe CNC kit PREMIUM BALLSCREW" kit? If so what was your results?

Thank you