Glad to see you got some nice nugs! I have a Blue Widow that I love and gets good reviews from friends. All said and done how did the nugs compare against the HPS you are used to?
For comparison purposes, here are the numbers from the Cree datasheet, assuming a Tj of 50c (lots of heatsink). This is the way I normally calculate efficiency, using the minimum numbers for the bin.
.35A 12W - 140lm/W - 40%
.7A 25W - 121lm/W - 35%
1.05A 38W - 107lm/W - 31%
1.4A 53W - 98lm/W - 28%
1.8A 70W - 91lm/W - 26%
Digikey's numbers are suspect because they report 5683 lm for a variety of LEDs of different color temps which is virtually impossible. They also use the number 6094 repeatedly. So take these numbers with a huge grain of salt. Digikey did not specify the junction temp of their test but if we use their numbers and assume their Tj was 85c
.35A 12W - 164lm/W - 47%
.7A 25W - 142lm/W - 41%
1.05A 38W - 125lm/W - 36%
1.4A 53W - 114lm/W - 33%
1.8A 70W - 106lm/W - 30.6%
For comparison, brand new 600 HPS bulbs are about 150lm/W, 40% efficient and 2200K. Of course we cannot compare these numbers directly with the LED numbers but it does give some idea at least.