I think comparing it to the Fenix L0D isn't a particularly good comparison since they are really in a different class from each other. The Photon Pro uses a AA and the L0D using a AAA. Sizing differences, run time -vs- light output, etc are largely driven by the battery. The Fenix is smaller and lighter. The Photon Pro is heavier, brighter, and has a longer runtime.
A better comparison, and one that I can provide is the Proton Pro with the Cree -vs- the Fenix L1D of which uses a AA battery. I have a friend who owns the Proton Pro, I own the L1D.
The Proton Pro wins longer battery life (because it can run at lower levels), better UI, has a low power red light built in, slightly lighter weight. The Fenix L1D has better power regulation, a nicer beam, and seems to be a slightly high quality of build. I have not seen specs on the maximum output of the Proton Pro in terms of lumens, but it the field they seems pretty similar on high.
If I didn't own a L1D now, and needed to purchase a light, I would most likely go for the Proton Pro, though the nitecore d10 is also interesting.
I am with David…
"you get what you pay for" doesn't seem to apply when considering surefire -vs- fenix. I have never heard anyone complain about the quality of the fenix product. Surefire is the older, more established brand. Fenix is relatively new. I think of it as the old establish luxury model Mercedes Benz / Surefire vs the more recent and maybe more innovative technologically Lexus /Fenix. Both are excellent… but the new guy is often a better value. Fenix is almost 3x cheaper than Surefire while having a high quality build and what most consider a superior regulation circuit.
The only thing I would ding most of the Fenix lights on is that their low setting is typically too high 11-20 lumens… where I think it would be good if it would be more like 2-4. In that way the surefire is "better", since it's low is 5 lumens.
As far as runtime and power regulation. If you look at runtime graphs between most of the Fenix and Surefire using similar bulbs and batteries taking in to consideration relative brightness, you will typically find Fenix has the edge in terms of consistency of the beam brightness and the amount of light produced over time. The surefire often has a longer absolute runtime because they often have a lower "low" setting and stretch the time by letting the light level fall overtime (e.g. not as strictly regulated).
Personally, I won't go for the Surefire E1B Backup because I don't like the 123 batteries. I like using AA because I can share them between a variety of devices.