I have an immersion circulator and love it. My passion is all types of cooking-not just BBQ. Plus, Milwaukee in January sucks for grilling or even just looking outside. I will always do grilled pork–chops, tenderloin, pork steak–this way. I've tried steaks but prefer them grilled (or pan-fried in cast iron) start-to-finish. I've done a lot of fish with results ranging from average to very good. I did salmon fillets and used a propane torch to crisp the skin (the only reason I eat salmon). Set off the smoke detector about a dozen times on that cook.
It really shines on cuts of meat that are susceptible to drying out. My wife and I sometimes get a food box for a few meals a week. Keeps us from going out to eat too much and they are easy enough that she can make them herself (she works part time, I work 80+ hours some weeks). We got a small sirloin roast as part of a meal kit. I hate sirloin–usually dry, tasteless, reminds me of bad wedding food. Used the immersion circulator with the seasonings included in the meal kit–probably just S&P. Can't remember the time but it likely 12-16 hours at 129° or so. Finished in a cast iron skillet again setting off the smoke detectors. Extremely tender. Too lean for great beefy taste but still pretty good.
My most daring sous vide exploit was a ~7-8 lb. Boston butt. I had a window of a few hours in December where the weather didn't suck but I wasn't about to do an eight hour or more cook. I started the butt like I always do; 225° on the WSM18, peach and pecan. After a few hours, I pulled the butt and immediately sealed it, adding nothing to the bag. I sous vide the butt for 24 hours at 190°. I planned to rest it and pull it at this point but the bark had disappeared so I put it under the gas broiler for a few minutes on each side. Rested and pulled adding the juices from the bag to the pulled pork along with apple cider vinegar (my typical pulled pork dressing). Absolutely amazing. I have one 12oz. bag left in the freezer. I'm going to see how it stacks up to the more traditional smoked butt method later this summer.