Is use Onyx and like it. I don't think it matters much. The most important part is to use a spectrophotometer.
Is Poster shop better than the standard RIP that comes with Versaworks which is Rolands rip?
I know there is no magic bullet for color management but if I can get a start on it with good programs than get a spectrophotometer in the near future than that will help.
Unless you think just getting a meter and keeping the Versa works?
Would you go out and buy it again if you had too?
To achieve consistent color on our printers, we archive our printed files on our server. This way if we need to print the same file on a later date all we have to do is transfer the file back to our printer. No need to re-rip. this is especially helpful because we are running 3 shifts and someone might not know how to properly set up the file.
I just attended a professional photographers workshop and the host, Scott Kelby, highly recommended the X-rite i1 display 2 for monitor color calibration. It's only $200. Calibrate the monitor every month.