Going to just start this off by saying I don't own every Sentinel and am just going off by what I know.
To put things simply, Sentinels have very little survivability on higher levels. They get destroyed easily due to low health, shields, and armor, and can only come back once per mission without the player using revives. Additionally, enemies seem to have the ability to instantly destroy a Sentinel twice. The Regen mod only helps to bring the Sentinel back to full health, but that doesn't help that much. It'd be nice if the mod could bring back the Sentinel multiple times (perhaps up