Hi Erick,
We're on Max 7.5 but I guess some of our experiences may be helpful. Note that there is a Service Pack for Max 8 already available ;-)
We found Max 7.5 to be pretty straightforward to install and run. We upgraded from Max 6 and it was pretty much a question of pressing the buttons on the installer.
BUT, the guiding principle has to be to test full and then deploy.
Use a new machine (i.e. one that has not been used as your Max server before) and install all the server components on it. Take a copy of your database, and convert it on the new server. Test it thouroughly on that machine.
Then if possible get a handful of workstation computers, and install the workstation components, and test them out thoroughly. Build some distribution sites ditto.
One thing to be aware of is any other software you use that used Btrieve or Pervasive. The change from Btrieve 6 or whatever to Pervasive SQL is a big one, and you may find that other programs are affected.
My advice is to not upgrade anything except your main address book. Do everything as a new install. So, when you are ready to roll out your full deployment, uninstall Max5, rebooot, uninstall Pervasive (if 5 used it), reboot, and then do a clean install.
This is not to say there is anything wrong with Max's upgrdae routines. I have just learned the hard way to do things the simple, long way than to use short cuts
Hope this helps,
- Pasta