Very interesting find. Here is what I have so far for CLU056-1825C1
Tj85C = TC60C.
Temp droop at TC60C = 6%
.044 V drop/ C
Nominal current is 2.25A and 51.95Vf @ Tj85C or 117W
the 3500K, typical lumens @ 2.25A Tj85C = 16791 lumens
That is 143.5lm/W at temperature, as GG mentioned.
If we assume an LER of 324 that is 44.3% efficient or 51.83 PAR W.
If cost is 40 euro or $45.5 USD, that is $0.88/PAR W
Cost matched comparison:
CXB3590 3500K CD @ 138W = 37.4% for $0.92/PAR W
Vero29 V2.0 3500K @ 79W = 40% for $0.90/PAR W
So this very large Citizen COB reinforces the theme, bigger is better. That said, for those who want more uniformity and willing to pay more/PAR W, the question would be how does the Citizen perform at lower dissipation W?