Malkoff lumens are substantially underrated compared to other companies using the ANSI FL-1 standard. One of the reasons that Surefire seemed to get a huge output boost in some of their lights was a switch to the FL-1 standard as compared to what most light people used to call "Surefire lumens," which were similar to Malkoff's ratings. However, dropins using a Cree XP-L HI will substantially outperform the XP-G2 LED used in the M61 that you linked.