Only $109.000 - vow thats a real bargain!!!
F-1 is not same as J-1, so that is a "white lie"
And there is not 80% chance of instructor job, it is -10% chance, recently met italian instructor who did go to Delta, its a graduate course, thats what gives you the F-1 visa.
You will only get work visa in USA if you get married there or win the lottery. So you better look for a wife also during your training!
I understand you have eye issue, and understand your situation, better if you use your money on another "cheaper and better flight school" in the US, because I have seen Deltas sales tech in action, and they know they can't promise you anything, sorry but true.
Regarding converting back to JAA later, will not be easy, if you are outside JAA renewal limits, but that does not mean you have to give up your dream. You can fly in many other NON-USA or NON EU countries with FAA license, but you need experience and hours. So why not take a cheaper CPL/IR /ME and FI course in the US, and use the rest of your money to get more experience and hours. Unless you get married in the US, no chance, but there are other countries in the world you can fly - and I think you could get something a lot cheaper then the overpriced Delta!
For foreigners they can not gurantee you anything, I was unfortunate enough to have to listen trough a seminar with them. You can get a lot of hours for $109.000, instead of being sent back to Europe with minimum hours after training with Delta, they said when they had their seminar that now was very down period for instructors etc., and they could only provide visa where you could work as instructor, but without pay. I assume the F1 visa, is a graduate 2 or 4 year program, might be different, but...... mucho dineros!