CaNo,
Welcome to the legend of the Lumileds RB100, get some

and enjoy the story. Waaaay back in September, 2007 Lumileds came out with the RB100 LED to compete with the Cree XR-E series. Lumileds had the RB80, RB90 and RB100 so the war was on. All was good with the initial RB series but one of Lumileds contractors then made a change to their epoxy that holds the die in place. This caused a large recall of all RB series LEDs from a specific date in October,2007 onward. The LEDs would fail when the epoxy failed.
I picked up my L2D RB100 in Sept 2007 and it was rated 150 lumens or so. The reason I picked it was the smaller LED should of had better throw, had a lower forward voltage and it was more yellowish than the sterile white of the Crees. The light was for helmet use and I ran it in 2AA mode for the winter. When light returns to the planet, I swap it over to a 1AA to make it smaller and lighter.
L1D RB100 VS L1D Q5 Now things get interesting! I have run the RB100 and Q5 heads on 1AA or 2AA depending on my needs. I LOVE the fact that I can tailor my helmet light to my needs with 1AA or 2AA. This is what I have noticed:
Brightness The Q5 is brighter than the RB100 but not by much
Throw The Q5 has more throw than the RB100 but not by much
Beam Quality The RB100 wins since the LED is smaller and not ringy
Runtime RB100 = 2 to 2.5 hours Q5 = 1.5 to 2 hours (RB wins)
Tint RB100 is yellowish Q5 is very white RB is better for viewing plants and off-road trails, the Q5 is better for the street.
These days I am using a L2D Q5 for a helmet light and my wife prefers the L1D RB100 since it is much lighter and has a longer runtime.
Personally, I am waiting to see what 4sevens has up his sleeve with his new series of 1AA and 2AA lights to see if they have more throw. The Cree XP-G has about 40% more output and won't have ring artifacts on the beam. The Q5 puts out 94 lumens per watt and the XP-G 132 lumens per watt so there will be a noticable jump in output. That is the puppy I am waiting for and they should be out near the darker time of Sep/Oct this year.
The standard L series Fenix lights use the P4 bin. The P4 puts out about 25% less light than the Q5, hope that helps.