As someone who really likes LED's, I agree that they can easily be overdone in brightness. That, and color choices are critical. It's really easy to go too bright and overboard on the color.
As much as I like cointaker, their "super bright" lineup is just too much I've found. The standard brightness 90's are generally much better, and even those can be too bright in some inserts. If so, their frosted are usually a great match.
Cool whites vs Warm whites makes a huge difference, and I've only used white for GI lighting so far.... not that there aren't spots I think would be good with color too. I love cointakers #44 frosted for GI lighting, particularly since they went with the newer housings that don't twist apart as much. For wedge bases it's a bit tougher as most of the inexpensive ones aren't rectified (Meaning flicker issues). WPC machines are even trickier to get looking nice because of the dimming circuit. I'm going to be going with Noflux Plus for my wh20, superfluxes in the backbox and domed frosted on the playfield.
I have to say though I've seen a pinbot done in red/blue GI lighting to match the playfield artwork. That looked really cool I thought.
-Hans