I just purchased my first LED kit from PinballBulbs (for my MB). Wow...the spotlights and well placed LED strips make a huge difference. All the bulbs worked and fit properly...no exceptions. I've been living with a half-baked LED conversion that I did a couple years ago. I'm happy to now have a fully baked solution from PinballBulbs. Customers service is also very good.
I don't believe Comet sells LED kits, but Art has a great variety of bulbs to choose from. I've been having a blast experimenting with many of Art's bulbs. Great guy and really does a great job supporting his customers.