I called Shaun and asked him a thousand questions so I could decide which machine was best for me. My first priority was to get the stiffest machine possible. The second priority was to get the largest one possible.
It turns out, the 1624 and the 2424 use the same gantry design, but the 2424 has a longer gantry. That means the 1624 will be stiffer. The smaller models use a different gantry that's not as strong. So, as far as I can tell from the information I got from Shaun the 1624 has the stiffest gantry.
Shaun also recommended the Bosch Colt router. I ordered that and it should be here any day. I also ordered the 1/8" precision collet from Precision solid carbide tools for woodworking and metal forming.
With the machine I ordered the Zenbot control box and Mach 3 software.
Shaun told me to expect 2 weeks lead time. I asked him to do what he could to shorten that The machine was ordered Jan 31 2011. Now I'm anxiously waiting!!!