Minimus AA is ridiculously uncomfortable vs. the 123 which i can wear all day long. They used the same neoprene pad on the AA as on the 123 but it's a much heavier, front-loaded light. For me, the AA version is unusable. I love the 123 version but frankly, I have switched to the Zebralight H52W for more output (280 vs. 100 lumens) with a single AA Eneloop instead of a 123 and it has a better runtime. The H52 is very light also. I view the H52 as new technology and the Minimus as an old revision, H52W wins on all counts (costs less too!).