I don't think you'll find anything 'off the shelf' near what you have.
I'm like you...I like bike lights. In fact I'm building a high-power LED bike light right now. I should get 1,000 lumens out of it and I expect it to last 4-5 hours with the battery I'll be using (Li-Ion). I'm really building it to compare against my OVERVOLTED halogen I built that puts out approx. 1,800 lumens (a 11w HID puts out about 550 lumens for comparison). If you're running your 50W at 12v (if the voltage is higher, the output will be as well), you'd be putting out about 1,650 lumens (depending on bulb).
So, if it's 12v, it's not superior to anything else (about 150 lumens short of my 20W halogen. BUT, my bulbs don't last too long either - only about 50 hours (fortunately, I can get them for $0.99 at Big Lots for GE) and my battery only runs them for 1:45 - long enough for a short MTB ride.
So, why would I build an LED that "only" gets 1,000 lumens? Run time! It's becoming important as I want to go all night with bright light. Carrying two batteries will get me through the night with the LED.
There's nothing rediculous about high power or it being illegal (people may flash their brights at you if you're on the road expecting you to get off your "high beam"). AND, if you're on the road, lights can save your life!!
If I could have them, I'd like lights so bright that bambi would not only freeze in her tracks, but also spontaneously combust!