I use single LED warm white or Retro LEDs in backbox, Single LED warm white under the inserts and good old #44 bulbs in all the playfield GI. Some places like bonus ladders flicker on and off when the score motor turns. In that case I put the #44 bulbs back in.
Even cutting back half the bulbs in a game to LEDs makes it a lot cooler when I bring it to a tournament or show and it runs all day long.