I'm a 2 stage DSer (not recommended but I started at 644 and was 90% belly lol) so I can speak about experience of the sleeve and of the DS.
The sleeve. Easy peasy recovery, sort of lol. Im a wuss! But eating resumed to normalish, but constant dieting, watching cals etc. Weight loss was GREAT.....for 3 months. Then it got really HARD! As someone who was SMO it should have melted off for another year or so. It didn't. I lost 100 in the first 3 months and then hit a brick wall. I contacted my team, who were no help at all. I had my OP on the NHS and in a hospital in London with one of the most popular surgeons in the UK. This meant and I had to figure it all out on my own. The struggle was real. I dieted, exercised (in the pool as after 100lbs off I became cripple) for 2-3 hours a day, 4 days a week.....for TWO YEARS! So for the 4 years I only had a sleeve I ended up losing 200lbs. I was 444lb when I got my DS.
The DS. My SAVIOUR! I must have some seriously jacked up metabolism because I still have to work and fight a lot harder than it seems other do. However, I am also MORE cripple now (hip replacement next month!! yay!) So I made a sedentary lifestyle look super active lol. I'm still losing, slowly, and in stops and starts, but Im also not dieting like I did pre WLS or pre DS, nor am I working out 12 hours a week. So this DS stuff is pretty cool.
There is loads of data out there, the nitty gritty is hidden in medical journals with a limited audience, but you can find nuggets here and there online via google.
Complications. Yup. That shit is REAL! I had several, will spare you the details for now, but I did write about it at the time on here. I have never regretted my DS as after struggling so HARD after my sleeve to be successful and falling on my ass, I knew in my heart this was the ONLY way for me to have a healthy and long future.
I'm now down in the 280's, nearing my surgeons goal (280) and I plan on surpassing that. Might I have been just as successful or even more so if I had the DS in one go? I cannot say, nor can anyone else. I learned a hell of a lot during my struggle with a sleeve. I learned I am strong, I am able, I am super wicked smart and that I am one persistent, stubborn bitch lol. I also had time, A LOT OF TIME between VSG and DS to learn everything that could fit between my ears.
Do your research, listen to your heart, acknowledge fear, but do not let it control you. Fear is the enemy
Good luck!