For the road bike purists this will probably give them extreme heartburn but I've completed the makeover of my 5900. What I've done is change it from a 10 speed to a 9 speed and changed the rear gearing with my most recent modifications.
I purchased the bike used a few months ago. It came as 10 speed Dura Ace and a 53/39 crank. I changed the crank to a 50/34 but left it 10 speed. I've done several centuries with a 12/27 rear cassette and for the long rides with grades 10% and below it works great. However, I realized that I needed a slightly easier gear for the centuries that might have a long climb late in the ride or have sections of double digit climbs. My cadence was dropping down into the mid 50's on the steeper climbs and that's just not healthy on the knees or hips.
So, after looking at the gear inch tables I installed a 11/32 XTR cassette, a Deore XT rear derailleur and a 9 speed Dura Ace right shifter. I left the front shifter, compact crank and derailleur as it was.
I'm really excited about this combination and hope it performs well on the road. It gives me a little more gear on the high end (50/11) and a good bit easier gear on the low end (34/28 & 34/32). I took it out for a brief shakedown this afternoon and the shifting seemed to be fine. It's certainly not in the class of all Dura Ace but if it will just shift when I need for it to I'll be okay with that.
Its giving me the spread of gears I'm looking for and keeping the weight at a minimum at the same time. In fact, I've now got a slightly easier gear than I have on my triple at 30/27 so I'm really excited about some of the tougher climbing centuries that are coming up.
The 10 speed equipment is not going to go to waste!! I'll give the 5900 a couple of good rides and then probably convert the Madone to a 10 speed using the equipment I removed from the 5900.
Here's some pics of the new drivetrain.