From what 17 owners described in owner discussions between January 2019 and December 2024. Owners rarely say which UMAi bag size they used, so these are reports from owners aging bone-in rib roasts, bone-in ribeyes and briskets in UMAi bags, the cuts this size is made for.
Bones are the recurring problem. Owners aging bone-in ribeyes and rib roasts describe the membrane never bonding around the bones, air filling the bag, and holes appearing within a day of sealing. When the bag does hold, the results are good: a 37-day bone-in ribeye fed 14 people, and a 14.3 lb prime roast gave four 25- to 32-oz bone-in steaks after 42 days.
Brisket gets a mixed but mostly positive report. One owner has done three to about 45 days with great results and another keeps several going at once, while one owner's 22 lb brisket was down to 10 lb after aging and trimming. Briskets taken past an owner's usual 45 days can pick up a stale smell.
Owners who want bone-in steaks without the sealing trouble sometimes skip the bag: one who has done both ages bone-in cuts in cheesecloth. For brisket, the bag remains the easy fridge option owners keep using.