I think the only one I'll be doing is the door knob color changing one. Fellow Pinsider jimjim66 lent me a bunch of different types of LED's and I tried about four different types in each of about four different areas on mine and the only one that really did anything for me is the red under the red inserts. Everything else, either the color was off, the entire insert wasn't lighting up, or there were voltage level issues. Some lights get a little bit of signal before they light up to "warm up" the filament, for LED's this means the light is on. There's also some voltage bleed from lights that are on the same circuit that results in some low level lighting from the LED's. The way I tested them out was to swap out different ones into the door panels on the right of the main door. That way, when the game is in attract mode, you can see 4 or 5 different versions at once and compare them to the originals on the other side.
I recently just cleaned the heck out of my inserts and even cleaned the bulbs(yes, they were THAT dirty) and WHAM, no need for LED's. Everything is super bright and lovely and fades in and out as programmed. I'm with Herg on this one. My TZ probably won't be getting LED's for a long time(aka when LED technology advances to replicate filament bulbs even more).
But it will get them at some point. It will happen.