First, fenixstore is a great place to buy from. Excellent service and quick shipping. You also don't pay extra for shipping.
I own both lights. Whichever you choose, I suggest you get the premium Q5 versions. They are a little more $$, but well worth it for the extra power.
I use regular CR123's in my P3D, so I can't comment on the rechargeable CR123 issue. If you get the L2D, though, don't use regular alkaline batteries. I use eneloop rechargeables and the work great, and will give you more power than alkalines. Energizer e2 lithiums will give you even more power and longer runtime. You can get some good deals on cr123 batteries at batteryjunction.com and lighthound. Lots of threads about good and bad cr123 batteries on this site.
It is hard for me to say which I like the best. I find the L2D easier to hold, because it is longer, but it is a lot easier to carry the P3D in your pocket. It is pretty impressive to put the P3D on turbo and see an amazing amount of light from such a small flashlight, but the L2D is certainly no slouch.
How often do you think you will be using the light? If you will only be using it a few minutes a day, then you will not run through cr123's very quick, expecially if you don't use turbo mode much.
So, I guess I am saying you should get both. :twothumbs