Can we load Ostfront and Operation barbarossa expansion pack for il2 with the new Unified installer 1.1 without sacking the game :?:
yes. No problems there.
i'd recommend however you use enjoyr packs from M4T with these addons - they will eliminate some of the incompatibility issues between different addons. But you don't have to, it will work without these too.
You can install the biggest one if you wish (BoE-TLD-Ostfront) even if you don't have all addons. You won't get all the content (you need the addons for that) but it will work, it won't break anything. It's the safest thing to do if you're not 100% sure which one you need.