You are definately one of the lucky ones.My friend lost her St.Bernard to Bloat.She rushed Emily to the vet,but lost her.She was only 8 months.And she was rushed in right away.
Here is a very good link to Bloat.Even though your furbaby has been through it,it could happen again.It will tell you how to prevent it.You really need to be carefull of what type of dry you feed.If only feeding him dry,I would consider giving him canned also.I hope this link helps.
I agree with Prin,you do need to take the healing of the surgery into consideration.
http://www.globalspan.net/bloat.htm