It looks really cool, as there are portions that I've never hiked before, and I'd like to tinker with more trail that connects through it. I have also read about experiences on the same John Muir Trail forum about combining the JMT and Tahoe Rim Trail. The Tahoe Rim Trail is 165 miles long and is part of the much larger 2,663 mile Pacific Crest Trail, which extends from the Mexican border to the Canadian border, spanning California, Oregon and Washington state. I think combining these two would be an awesome, extremely adventurous 376 mile experience.
The third option and the one I'm most leaning toward is combining the JMT and the 49 mile long High Sierra Trail. I think it would be fun to hike the John Muir Trail southbound, rest and replenish in Lone Pine (near the JMT's southern exit, Whitney Portal) for a couple of days, then head west toward Lodgepole in Sequoia National Park. I've hiked portions of the High Sierra Trail, and it would be nice to complete it this summer.
I am taking more precautions this summer in order to prevent injuries, and foremost among them is reducing overall pack weight. I always experiment with different types of equipment in order to reduce weight, minimize the amount of items I bring, save room, improve weight distribution, and the like, and this summer I think I'm going to experiment with taking only a backpacking tarp for shelter. Another major experiment I'm considering is not bringing a stove and fuel canisters. I've read about an extreme minimalist who pours water into his dehydrated dinner packets in the morning and fastens it to the top of his backpack with foil under it to reflect the sun all day, and in the evening, when it's nice and hot, he'll eat it. I think that would be very interesting to try.