I've tried this, but unlike others had very poor success: have a 1200 watt sous vide. Would heat strike water a via my burner, add that to my mash (biab), then add the sous vide stick in a hop spider, to keep all the grains out of it. Doing temperature probes around the bed, I saw radiating heat: clearly the wort around the sous vide I was at the right temp, but everything else: fell off pretty dramatically over time. I'm not sure how you expect that tiny impeller on the sous vide to recirculate the liquid through all that mash. Based on that failed experiment, I jury rigged my own K-RIMS setup, and it's been working great. The sous vide still makes great steak though :-)