Here at Midas in Towson, MD we use Activant with R.O.Writer on a daily basis. It (Activant) does integrate rather seamlessly with R.O.Writer. Overall, it is a pretty good cataloguing system, as long as you keep your updates current. We are sent a DVD at the beginning of each month that must be installed on all terminals within the system. This is crucial!
The only downside to it is the lack of computerized engine parts included. For example, it's almost impossible to give prices on any sensors, solenoids, etc without calling the individual vendors on these jobs.
Other than that, I have no real qualms, and would recommend the system.
Hope that helps...
-=Mike=-
Mgr. - Towson Midas