About 1500 users in our environment - slightly less than that for pc's since many of our machines are used by multiple people. There are 2 of us that manage LANDesk & do deployments to machines. We have a tech staff of about 5-6 others that are available to assist with pc replacements. Usually we deploy the image in the IT area - usually because it is a quicker transfer as we can hook direct to our gigabit switch in the back room rather than run over the 100 mb lines that some of our areas are still at.
also, we have our images currently set as off the domain, so we name the pc & join the domain prior to physically replacing the pc anyway. Otherwise, if we drop it at a user station & image from there, it will impact the user for a much longer period of time.
Finally, there are some items that cannot be imaged - we have laptops that contain patient data & must be full-disk encrypted & be installed with our tracking software. We alsi use a web filtering platform that uses an installable agent for when the laptop is off-network. All 3 need to be installed manually post-imaging.
We usually image a bunch at a time so we have them ready to go as needed. all we then need to do is rename, join the domain, swap the pc & go, & install any additional manual add-ons for laptops.
We try to direct our users to store to their network drive as much as possible. On our desktops, we also have Office pointed to the network drive for the autosave & primary save location. There are some limited files stored locally (desktop, etc) that they may need back, but we can always drop them on their network drive before or after the swap, then drop a shortcut to their files on the new desktop.
I think it really comes down to preparation time vs user impact time. The more we can get prepped before getting to the end user, the less time they will be down.