The way I understand it from the earlier posts of Brad and others, there is no activation limit as such. Stardock's the guys behind the Gamers' bill of rights, and while not all games on impulse adheres to it, all games BY STARDOCK does. Important distinction that is often forgotten, causing a lot of senseless arguments.
( Link: https://forums.sinsofasolarempire.com/?aid=322522 )
It is also interesting to read Brad Wardell's explanation of the points, which is a lot more helpful, really.
Also, the security system in question on Elemental is 'Goo'. One of its features is:
"It paves the way to letting users validate their game on any digital distribution service that supports that game. One common concern of gamers is if the company they purchased a game from exits the market, their game library may disappear too. Games that use Goo would be able to be validated anywhere."
(From https://www.stardock.com/about/newsitem.asp?id=1214 )
For instance, the thing is that the gamers' bill of rights doesn't mean NO drm, it means that the security is one step removed - it's with getting updates. I find that fair and reasonable, however; I do believe the archive option should fit your needs; it should let you archive the game and restore the archive - including updates - without getting them online. So if Stardock says 'ABANDON SHIP!!', archive everything and put it on blackrays or whatever storage medium is popular at the time, and you should be fine.
I say 'should' because few use it and I haven't seen much feedback on it, and I believe it didn't actually work for a time. That is hopefully fixed now (Usually finding a problem equates with finding a solution shortly thereafter).
As for the activation limit, it is never stated. It is not a fixed limit, like the 3 times total limit, but rather one that is designed to prevent large scale distribution of a single license - AKA, 'piracy'. 5 reinstalls a day? No problem. 42 installs on 29 computers a day? A problem. (Example Numbers are in the support pages).
However, for those using backups/reinstalls a lot, they mention this:
"Backup and Restore
Backups of your PC should include your operating system installation and the SIG.BIN in the application directory that contains your activation information.
If you restore or reimage your PC frequently, be sure to include the OS and application as part of the backup. If you reinstall the OS from scratch (like from a bundled restore CD), you will need to reactivate." (http://www.impulsedriven.com/support/activation )
So, an activated backup REMAINS activated through a backup, if you follow these guidelines. Still not EXACTLY what you need, but still, many of your main issues seem to be covered allready.
I hope this is helpful. The biggest concern for my part is lack of backwards compatibility for OS's, combined with Microsoft's sometimes blatant or heavy-handed attempts to push people into a new OS. But then, I've used Impulse and it is a much 'safer' platform than, say, Steam. Also, while it doesn't give in-client options to sell used games, Stardock says that this is handled through support, unlike other DD's which says 'no-can-do'.