Brian, thanks for your comments.
I'm fairly confident that I can make the 20 miles a day, I frequently do 22 miles and 5,000 ft of ascent in 7 hours at sea level. I've walked at considerably higher altitudes than Whitney peak and done good distances. And at the 6000 – 10000 ft mark that most of the JMT is, I don't anticipate altitude being a huge problem. I'm heading SOBO, so should acclimate as I go. I'll be training hard, and plan to be at peak fitness the day I hit the trail.
I am going cookless. A mix of energy bars, trail mix and nut/chocolat butters should see me fine for a few days. I'll be able to get real food at Tolumne, Reds, and VVR and pack a few treats in my re-supply at MTR. So there will only be five days of "hardship" until I get a cheeseburger at Whitney Portal.
That pace will require me to eat 3,500 calories per day. I'll drop a few pounds, but that's part of the reason I hike anyway.
The solar charger is for the iPod and the Suunto. I know I can recharge at Reds, but I'm not planning to stay there long enough to get a full charge. The Solar charger I am planning to take is much more effective than anything that was available in 2008, and has a larger area than most portable ones available today..
Creek Crossings – not sure! I was planning to wear my boots through, certainly that's what I do in the UK. They dry quickly enough afterwards. But this is one of the things I need some guidance on. How many crossings are there, and how deep will they be late in a dry year? What do people do if they don't wear their boots? Bare-foot it, or carry something for crossings. I could throw my Five-fingers in there, I guess.
Advice I saw on an gear list said to use a twig to dig. I was planning to pack a Sea-to-Summit Trowel at 75g. Wasn't sure about taking poles – I didn't list them, and I don't usually walk with them. But I'll consider your advice with respect to sleeping gear, and take the poles if I still save net weight.
Clearly a tarp would save me weight over my bivy, but the quilts I have seen rated to 26 degrees (as my bag is) are expensive and do not save me much weight over my sleeping bag – 150g for the MLD one. I presume you are advising tarp/bivy/quilt? Once I add a groundsheet I'm not sure I'd save enough weight to justify the expense. I'll look into it.
As for the Cuben rain jacket – I'm hoping that needing it will be the exception, not the rule. So I doubt strap wear will be a concern.

I hope to see you on the trail.