I've got an L1D and I've never seen an NDI in person.
L1D: $55.20 shipped from fenix-store.com with CPF8 discount code (or $67.16 if you get it as part of the 4in1 pack, like I did)
NDI: $79.90 before shipping, but tadgear.com is out of stock.
L1D: Max 120 lumens for 1.5 hours (according to Fenix).
NDI: Max 190 lumens for less than 40 minutes on an alkaline, or about 1.5 hours on a 14500 battery (according to tadgear.com).
NDI: Min 3 lumens for 50ish hours (or 5 lumens for 60ish hours on a 14500).
L1D: Min 12 lumens for 25 hours.
NDI: Infinite programmable adjustment between min and max.
L1D: If you don't like 12 lumens, 53 lumens, 107 lumens or 120 lumens, you're out of luck.
NDI: Has a strobe mode.
L1D: Has a strobe mode.
NDI: Everyone says it has great build quality, and I have no reason to disbelieve this.
L1D: Mine has great build quality.
NDI: Forward clicky.
L1D: Reverse clicky.
I didn't get the NDI because I was able to get a smaller light for EDC (my P2D, part of the 4in1 pack) without waiting for the NDI to become available or spending a lot more money. The L1D alone would have made a great choice for me too.
If you are willing to wait, and want the NDI's features (programmable light levels, a very low low, more output, forward clicky) then it's your choice. If you're too cheap or too impatient you will probably be very pleased with the L1D. If you want both a 123A and a AA light, you should get the 4in1 pack like I did.