I finally finished stuffing around with LEDs in my Firepower.  Overall I reckon it looks pretty good.

I posted a video of attract mode here;
http://picasaweb.google.com.au/shawvale/PinVids?authkey=Gv1sRgCIPxrfKC0M3xDA#5493143909425751874

It's my first video and it seems to have degraded a bit though the process of uploading to Picasa - and maybe I'm a crap videographer  

All the LEDs were Cointaker brand.

Some comments and things I noticed were;

• you need to align the LED centrally in the insert or it looks pretty bad
• used warm white frosted for the GI - they end up a lot brighter
• the bonus tree looks significantly better than incandescents , they are just so much brighter and cleaner
• used frosted colours to match the coloured inserts, seems to make the colours stronger, except orange
• the purple changed the power inserts (rh midfield) from a pinky colour to purple. This was the biggest difference
• the frosted seemed to work better on inserts with writing on them
• the orange frosted wasn't so good, too dull compared to the others, the LH target arrows are frosted warm white, the RH one frosted orange
• in the bumpers I used the bumper 4+1 hi power warm white but there wasn't that much difference to just using a single warm white
• used 89 coloured flashers in the red and blue large arc inserts, I think the flashes produced are of a slightly shorter duration
• used wide angle in the larger red insert at top - not frosted.  The larger inserts are about 28mm diameter and normals are a bit small, like the orange shoot again between the flippers, the regular inserts are about 22

Hope this helps anyone thinking about using LEDs.