A thread I can relate too, don't know where to start, lol.
First light was a Cateye EL 135. Thought two was enough. Used it on MUP as an emergency light. Not good enough so added a Powerbeam on helmet. Then I took on commuting. Those mention light was making me very stealth and almost became road kill. Major upgrade was in order. Came to BF and learn this thing called DX P7. Bought three of them and used for two month. Switch drove me nuts. Bought a SST 50 Rocket from Shiningbeam. Cool bright light so I bought two of their X thrower. These were hungry for electron juice. Put the SST 50 flashlight aside and join the MS900 club. Good floody light but a bit too floody and not enough throw. Gemini Titan came along and I bought one of those. Found a good combo using the Titan with two SST 50 thrower. Waited until Bikeray IV came out.
As for Helmet light: I tried the old P7 but not enough throw. Used the SST 50 rocket then switch to the SST 50 X Thrower. Shiningbeam then came out with the XPG R5 Rocket. Used that unt MS came out with the XML.
Current setup as commuting lights:
1 x Bikeray IV
2 x Mg X Thrower SST 50
1 x MS MJ808E XML
Most of my old light went to my backup commuter or to my SO bike who is loving it as my SO who gets them for free. My old P7, SST50 and xpg R5 are used as household flashlight along with the 30 18650 cell I got. Last time we had a power outage, I had two flashlight I'm every room. Neighbor thought I had the most silent running generator they ever heard.