I bought an older 120 light from another member here, and was lamenting that I didn't wait to pick up the 140 lumen version.
Other than big jump in horsepower (20 addl lumens), perhaps the main difference between the 120 and 140 lumen version is that the latter were exclusively ACME; some of the 120s had 24TPI threads and some had ACME threads.
When I received the 120 in question, I immediately unscrewed the original 123 battery tube and replaced it with my 18650 tube, which is definitely ACME. Since they screwed together, I was fairly confident that I had an ACME head.
I want to get the firmware upgraded in this head, but according to the HDS website, earlier versions (non-ACME) might be excluded. Just trying to confirm before this light makes its once-in-a-lifetime pilgrimage back to Tucson.