Keven, you are of course free to get whatever operation you feel is in your best interests, but I don't really understand the reasoning presented in your post. Either the sleeve or the DS would allow you to start losing weight right away, as the sleeve is part of the DS. It is unlikely, given your present bmi, that the sleeve would be anywhere near adequate for the amount of weight loss you need, and you would lose the opportunity to have the synergy of the restriction of the sleeve and the malabsorption/metabolic changes of the switch working for you simultaneously. You would also almost certainly be committing yourself to a second bariatric operation.
It's your choice and I wish you the best with whatever decision you make, I just don't understand your decision.