Solus3 has actually improved a good deal [bugfixes] at least since it was introduced. We migrated fairly early on [ In fact, It was around September/October 2011], and the first couple of updates were a nightmare - albeit out sims setup is more complicated then some other schools I believe.
For example, last Friday between 3pm-5pm we updated FMS+SIMS to the autumn release - our internal support system where staff report issues with pc's picked up 3-4 issues from staff regarding sims not updating. That's now down to manageable levels -> with our tweaks around solus2, I'd ultimately end up having to fix a similar number of pc's.
To give you an example of 'our sims setup is more complicated'. We have 3 FMS databases, 5 FMS workstations, push sims out to ~100 laptops and ~3-400 workstations that may be used by staff.
Capita do still have some areas where improvement can be made, and some flaw's in the process - however, it I've got to the point where i'm fairly confident that a solus3 upgrade will run smoothly.
a) As it was said in an earlier post - if you run WSUS [windows updates service], or can push out dotnet 4 by some method - get that onto the any laptops/server first. (We are lucky that we have windows 7 across site, and the deployment process automatically runs wsus, pulling down all updates including dotnet4.)
b) If you rebuild pc's a lot, make sure you think about keeping the solus 3 database up to date
c) Set up the service to auto download updates to end devices but NOT install them - you can get the updates downloaded to the workstations ready for when you 'upgrade' i.e. once capita do a new release allow time for the solus 3 agents to get the setup files locally ready for the install
d) Staff tend to miss the notification about solus3 asking them to close sims - so pick a time when they are not in. If you do do a sims update when people are around, they'll miss the update window, go to move screen in sims - which will crash as the DLL's version do not much. Trying to go back into sims will similarly error - rebooting the pc allows the pending file operations to complete.
Paul