StoneyCNC, Good post, I have learned several things here;

1. Use linear rails
2. On a welded frame use the jazz method of bolting the top member where the rails attach so this can be shimmed as required.
3. Try out the Linux software before buying Mach 3

You are under commercial pressure whereas I am not, that makes a big difference and I agree with most of what you say in that respect, also I was surprised you went to such lengths on this forum as it is clearly aimed at DIY self builders. I started out with the intention of buying a machine but after reading the information on this site and seeing the difference between self builds and some of the flimsy commercial offerings I have decided to self build. Best of luck in the future with your product.