I have the temp set at 135, So they have dropped from 165 to 135 in a controlled environment and they will stay at 135 for as long as I want them to. I usually go at least 24 hours, sometimes 36. If I was to go at 165, I'd hold for 12-18 hours probably. I've also done awesome medium rare briskets that have never went over 134 but we're fully tender and amazing.
My understanding is that when you take beef or pork slowly up to 200 outside, it eventually breaks through and gets tender. When you take beef or pork to a lower temp indoors via sous vide, that works because the temp stops and never overshoots and enters the dry stage that requires further heat breakdown, like it will on a grill because the girl is always hotter. Also, no one's going to want to hold, not cook, meat on a grill for half a day.
Is that about right? I skipped over the part about how sous vide necessarily captures/seals moisture because of the bag but obviously that's a big part of it too.
Really intrigued. Use the outdoor machines for what they're good for (flavor) and the indoor for final control and logistics.