I run the 20k bulbs. I have:
3x Plusrite DE 250HQI's over the 125
1x Plusrite Mogul 175w 20k (formerly over my 29gal, soon to go over the fuge).
My impression is this:
The 10k bulbs are a bit more yellow than pure white. The 14k bulbs are more whitish, think 10k. The 20k bulbs have a nice white/blue color to them, think 14k. I'd put the Plusrite 20k color closer to a Phoenix 14k in color.
I haven't taken PAR readings, as I don't have a meter. But as far as budget bulbs go, they work -great-. For the price point, I wouldn't hesitate to give them a go. You can replace these bulbs every 6 months and still pay as much... or less! than buying an overpriced name brand bulb. And no.. you don't need to change halides as often as the manufacturers/dealers want you to.
My personal opinion: Name brand halide bulbs are a total ripoff at their price point. The so-called replacement schedule is a sham. Do you change your oil every 3000 miles? I don't. It doesn't need it, but the companies that sell the filters, oil, and do the oil changes would prefer it if you changed your oil as often as possible to maximize their profits. Many modern cars, especially if you use a synthetic or partial synthetic, can push 10,000 miles between oil changes. My car does, and the engineering spec states this.
So, as with your lights. Change them when you need to, based upon your usage. Light schedule. Livestock. Etc.
