I've got a L1 (actually two, both the Luxeon and Cree) and a D-Mini. I like both a lot but can't help thinking the L1 is fairly priced and the D-Mini is overpriced.
I know that LumaPower produces great lights, but the D-Mini is almost the same price as the L1 (that is if you know where to buy it). The L1 has Surefire's awesome warrantry, top-notch build quality and is American made.
Not that there is anything wrong with lights made in China, but frankly given labor costs and the lesser-known nature of LumaPower, the light should be cheaper.
Just my $0.02