I did, always loved the exterior design.
Long ago I contacted a few members of CPF to mod my Arc4.
Newbie took on the challenge to gut my Arc4 and he made it a single stage twisty with momentary push.
I'll never forget that experience, he did the mod for free but it took ~2years.
Here's his thread on it:
https://www.candlepowerforums.com/threads/59275
Later on I contacted datiLED and he swapped out the lux for a seoul.
I remember Newbie mentioning how hard it was to get apart, the other problem was the fixed reflector.