Phil,
I can see the difference already. Put it this way, you wouldnt even see the colours from that far away if they were normal bulbs etc, thats how i know how good the Led's look. My brother walked in last night and from 10 metres away, saw Independence day and said instantly, how good the Led's looked. Normally, from that distance you cant see anyt colour.

Wotto, hi mate. 

Something I have found, is that Bally/Williams inserts seem to be thinner and much more transparent (carries light thru much easier) than the thicker inserts on Data East/Sega. Thats something I have found instantly on Bally/Williams versus Data East early (1990) or later 1996/1997 later models of data East/Sega. The inserts seem to be thicker on anything else than Bally/Williams.
 So, on a Bally/Williams, u CAN get away with some Led's if ya want, but on data East/Sega etc, once u do one, u really have to do all inserts etc. The Bally/Williams patch gets rid of the small strobing on most Bally/Williams etc.  On the other manufacturers etc, the strobing is the same, but not that much to stop me from putting LED's in all 35 machines (yes, I am on a mission).

It just brings pinny's into the 2012 year n look. Reallistically, the std bulbs look good on anything prior to DMD etc, and I would not put LED's into say the 1978 model Phoenix, but all other machines, the answer is a resounding YES. and I used to be on the fence. It really makes a big difference and makes boring lifeless inserts come alive. I really reckon LED's are the way to go to modernise the fleet, if that makes sense.