you people all confuse me so much tbh. Just because the eagle has a 20 man capacity doesn't mean you have to use it. If you're worried about 'all your eggs in one basket", stop putting 10 man terminator squads in.
I see the eagle as a land raider substitute, trading durability for mobility. different slots have an effect on the matter and the fact that you can take a dedicated transport land raider for termies is also a key factor though.
Seriously though, if you want to get "the most" out of a storm eagle you dont really have to put 20 men in there. IMHO thats a bit of a dumb move. Treat it as a flying land raider