I know you are talking about sidelights, but if its of any use I used to have the Ring Sportzblue bulbs as my normal headlights (dipped beam H7 bulbs), and in my opinion they were unrivaled. Pure white light with a hint of blue. Many people actually thought I had xenons. Highly recommended! Also I never turned my lights off (literally), and only one bulb blew in the course of 2 years.
They were 80W bulbs though, which I gather are illegal for road use. I didn't have any issues with the law, and I don't know about MOT as I never kept the car long enough!