Off the top of my head -- a folder on Dropbox that you dump your Saved Search files into, and each Mac has watched folder triggered macro that copies the new/changed files into ~/Library/Saved Searches.
They won't show up in the sidebar unless you add them, but they will be available to mdfind.
Remember that search paths etc are absolute -- if you have different short user names on the Macs you'll have to do some editing (which wouldn't be difficult to do programmatically, as part of the copy step).
I haven't done much with this macro since I wrote it, as it's not one I personally use, so I haven't done any digging on the saved search location issue. But using @Nige_S' method posted above seems like a good way to solve the problem.
Yes. In fact, as the smart search folder only needs to be set up once (it is a set of rules rather than a list of files) I think I will make a macro to copy it from somewhere in Dropbox to the Library/Saved Searches folder on the new Mac. Then when I am setting up a new Mac I can run the Macro to copy the smart search over to the correct place.
I actually use an adapted version of it multiple times a day. I would say it is actually my most used Macro So, thanks so much for posting the method!
Opens the path with a call to a subroutine named 𝗌.𝗳𝗻𝗱⇾NewTabOrWindowInSpace (included with Finder Assistant).
I realize that this is highly customized to meet my needs so I won't clutter this thread with a download. But if anyone is interested, just send me a PM.