I had a previous WLS that was 'restriction only' and it did not work for me.
That left RNY and DS. Actually at the time of my research, I did not know about the DS until a couple of vets and a surgery war clued me in.
I was about ready to say no surgery at all if all that was available was the RNY and here is why:
30% possibility of dumping - (who the hell wants that??)
malabsorption quits for almost all in about 2 years and all you malabsorb after that is your vites.
NO pyloric valve which causes a plethora of problems, like reactive hypoglycemia (HOLY CRAP)
There is more but I will be here all day.
DS:
98% cure for Type II diabetes
Statistically the best surgery to get the weight off and KEEP it off.
The most "normal" way of eating
I had been on some sort of diet for 40 years and I was tired. I weighed in at 279 but if I had not been dieting all those years I probably would have been 400# - 500#.
I was so convinced that the DS was the surgery for me (and I could have had the RNY paid for 100%, right down the street) I robbed my retirement and flew thousands of mile to a foreign country to have the DS. I would do it every year if needed.
Here is a good link to read:
http://www.obesityhelp.com/forums/DS/4059577/Comparison-of-D S-and-rny-good-info-if-youre-trying-to-decide/
Good luck with your decision!