Appreciate the insights. I'm not too worried about Altitude, I've been to 18,500ft (summit of Elbrus) and summit of Whitney before and managed OK - nothing more than a manageable headache. And heading North to South (as I hope to) means Mather, Pinchot and Forrester passes give me opportunities to acclimatise.
Time wise Whitney took me 9hr 27min http://connect.garmin.com/activity/12475943 to cover what my GPS said was 20.4 miles. I'll be aiming at an average 20 miles a day on JMT and while I'm guessing some days might be quite hard - none should be as hard as Whitney was.
By solitude, I wasn't meaning while hiking, but after lights out. I plan to walk hard all day, and stop at the best place I see after 18:00 each evening, rather than have set targets in mind. But since I plan to graze on food all day long, rather than have a big evening meal, and since I do not plan to cook - I'm not sure what chores I'll have beyond washing and dressing, making a breaking camp. I'm guessing once it goes dark, I'll be bored, and maybe a little scared.
But I realise I'm a noob, and many of my assumptions will be wrong. I can live with a little tedium, I just don't want to make mistakes that will cost me.
As for VVR/MTR, I read that MTR "suggest that you arrive at Florence Lake before noon on your arrival day to allow for the time it takes to ride the ferry and hike in to the ranch." which seems more of a time suck than VVR, since that has a ferry at 16:45. As for nipping in to Mammoth (where I have spent good times snowboarding in the past) how does one arrange transport to do that? And where from?
I realise the choice of bear canister is going to be an important one. We can't buy or even view these things in the UK, so this is going to be a difficult choice. A guy on here reckons he does the whole thing using a Bare Boxer 101, and I'm hoping to do the same - using Mainstay, Nuts/seeds, Protein Bars.