UK sellers quote 1.5 hours for the L2D Q5 and I get between 1 hour 45 minutes and 1 hour 55 minutes on turbo before a noticeable drop using Panasonic Infinium AA 2100 mAh and Panasonic AA 2600 mAh.
Light reviews gives 1.5 hours for your model using 2000mAh Eneloop:
http://www.light-reviews.com/fenix_ld20/runtime.gif
Here is a thread by 'selfbuilt' who finds 1 hour 10 minutes for the LD20 on turbo using Sanyo Eneloop 2000mAh:
https://www.candlepowerforums.com/threads/214890
This UK seller quotes 1.3 hours on turbo using 2500 mah Ni-mh batteries:
http://www.fenixtorch.co.uk/led_torches/fenix_LD20.html
That is not so far off your values. I think that rechargeable NiMH batteries need a number of charges to 'bed in' and fresh ones will not be quite so performant.
Some values quoted on the Fenix site are here:
http://www.fenixlight.com/product.asp?classid=2&Page=2
The above gives 2.4 hours for the L2D Q5, and the same site quotes 2 hours for the LD20 Q5. Mmmm. The Fenix web values are cack. Poop. Soft and steamy. Clearly someone has been smoking crack. You can't even pull the LED Lensor trick since the Fenix lights are regulated, and when the output drops, it does so fairly dramatically.
Oh yes, one last point. There are variations in cells, and some tests find that Japan made ones last a bit longer than Chinese made ones. And some makes last a bit longer than others. Light reviews gets consistantly long times and he uses Sanyo Eneloop which are consistently good performers though I have not seen detailed tests against other makes.