Bradshaw,
These 'engineers' designed the new Yukon as an all-in-one unit that allows the user to select from LED's for trail, or in-camp chores, and the incan bulb for when it's needed. I can recall many occasions where route finding at night would be utterly impossible with an LED. When it's pitch black and your route markers are camouflaged every 100 feet, at best, no LED (with the exception of the 5w ls) is gonna help your plight.
Carrying a seperate bulb module around for the Solo is rediculous for real-world application, as no one is going to want to take the time to change out the module back and forth every 5 minutes, based on light need. Additionally, the Matrix light output is pathetic, unless you're planning to be in the backcountry or underground for 2 weeks' worth of nights on a single battery change...but then again, if you're gonna be out that long, why not take a brighter light and a change of batteries? A Photon keychain light puts out as much light as the bulky Matrix. If you REALLY need 40 hours of light, take 3 Photons...saves weight, space, and gives you an added degree of redundancy. The point is, Princeton Tec is using much brighter LEDs than those employed by the Matrix. Just as the modern farmer has relegated the sickle to antique status, so will the Yukon obliterate the old Solo/Matrix combo.
For what it's worth, I've used the Brinkmann focused LED headlamp. Construction is far-inferior to Rayovac's 12 dollar LED Combo headlamp, readily available at most Wal-Mart stores. Light output on the Brinkmann is so tightly focused that it's worthless as anything but a long-distance illminator...As a long distance illuminator it fails as well since it uses only one standard 5mm LED and isn't bright enought to perform the intended roll. I guess if you're satisfied with the Matrix and the PR-2 LED bulb, then you might just be satified with this though. In my opinion, a disappointment in quality as well as light output make this less usefult to me than the lead paperweight on my desk.
If they used an LS instead of a 5mm LED, things might have taken on a whole new light.
So far, my all-around most useful headlamp is the aforementioned Ray-o-Vac headlamp with a 1w LS side emitter mounted where the incandescent buld would normally be, and the two red LEDs swapped for white 5mm Nichias, giving it the option to run 1 LED, 2 LED's, or the LS for long range light. I still require 'high beams' when I'm hiking off-trail, and a PT Tec 40 fills that need...but for everything else, the LS or LEDs are a nice combination. The only thing I don't like about it is the 4-5 hour runtime I get with the LS (since it uses AAA batts). Hopefully the PT Yukon will take it's place in my stable of headlamps and finally let me use lithium AA's again, like the good ol' days.