Just put one in to replace a Hamilton 10K sent back for being very yellow. Too soon to tell, but next to another Hamilton 10k, it's similar just a hint of blue. My LFS uses the 400W and has similar results. Personally, for me the Hamilton 10K is about $50 and the AB 10000 (13K) was closer to $90. I run actinics so the "hint of blue" from the AB isn't worth the difference in price. No spectrum measurements, just pure personal preference.