I bought my glowshifts almost a year ago, I had my boost gauge only glowing red, it was something faulty in the wiring...sent gs an email, I sent it in and 3 days later had a brand new replacement. Have not had any issues since. As far as accuracy, they are right on with my Edge CTS readouts sooooo take that for what it's worth.
I've learned in my searching around that most people that have good experience with any kind of products, you rarely hear from...because there are no issues.... people that do have issues, want to tell the whole world about, and it usually ends up with a bad rap. As far as glowshift goes, I am extremely happy with the product and their customer service and would buy from them again. There is a potential for recieving a bad product no matter what company you buy from, not everything that comes off the assembly line will be perfect. Just my .02!