suggest you look at
http://www.torchythebatteryboy.com/ website for some comparisons of light intensity and spread.
I bought the 4xR5 1600 for about £79 last year and the beam on the top setting is good for 30+ mph downhills on unlit back roads. I ride 12.5 miles each way and get 3 days (~6 hours) on (mainly) the low setting which is adequate before it glows red for 25% left, it is easy to flip between intensities between slow and fast bits and it doesn't ever index to off like the old smart lights.
On single lane back roads cars stop in lay bys to let you through, (I often put my hand over part of the lens to protect them from being blinded).
Fortunately/ unfortunately LED lights are now so bright that they will prompt legislation for bike lights to be dippable/ shielded.
Torchy sells as the big_f_d_d on
ebay.
He also sells mounts which seem rather pricy at £9 (for what they are) which allows me to transfer the light in seconds between the mtb/ hybrid/ cyclocross/ tandem depending on my mood (and my poor maintenance regime).
My prev light was a Niteflux 12W Photonmax that cost £300 that was great when it worked but went back to Australia 3x because it never woke up after the summer layover. My only gripe on the Fluxient is that the flash mode uses the high power setting. I preferred the Photonmax mode of 25% brightness when flashing.
I also carry a XML-6 12850 single rechargeable cell in the pannier just in case (not that I have ever run out on the main light) and loads of Blackburn Mars (3s and 4s) on my back, bike and spares in my panniers. (And a handlebar end lights- for redundancy and in worse weather).
Good luck in your quest, ......