Since it's been requested more than a few times, and I have both 14k and 20k Plusrite bulbs, I just put together a comparison photo. My tank is a 75g with dual 175w magnetic ballast mogul style MHs. As far as appearance goes, the 20k are much better in my opinion, and the opinion of the few people that have also witnessed them here in person side by side.
These photos were taken with no ambient light, just the tank lights in an otherwise dark room. The camera settings are identical for both pics, as was the tripod setting. The photos are unedited aside from cropping and combining them. The 20k bulbs are around 2 months old, and the 14k's are around the same.
anyway, here is the pic. I don't have a par meter, but to my peepers the 20k bulbs are a bit brighter overall. The photo loses some of the glow the tank has in person obviously, but it is pretty close to accurate as far as the general color goes... though the 14k is not quite so yellow looking in person
Do I think they are good bulbs? Absolutely. growth is good even on the 20k, color is very good... I have no complaints, I did have one show up broken, they sent me a replacement immediately after i sent them a pic of the broken bulb. Shipping was fast... 100% satisfaction, I see no reason anyone would need an 80$ bulb. I stocked up on them
