Update: 03/17/2014
La Sportiva has their Pegasus buckles available with individual SKUs if you want to pick some up to mod your TLT6. The buckle I used was the lower one at the toe of the Spectre boot. It’s worked well for more than 50 days of touring, only issue is the length adjustment gradually loosens. But it takes only seconds to re-adjust using the super functional “bicycle brake adjuster.” More, I’ve found that the B&D UCP Ultimate Cuff Rivets are working beautifully. My install has not loosened up. For months now I’ve been enjoying the friction-free and nearly zero play cuff configuration on my TLT6 boots.
Dynafit TLT6-P is the finest boot Dynafit has ever done — and easily the best boot on the market for ski touring that involves lots of human powered vertical. But nothing is perfect and I have a workshop.

In a previous mod I replaced the cuff rivets with removable fasteners. Easier to work with the cuff off the boot, but not essential.

Main order of business is the pesky side buckle. TLT6 buckle configuration is improved from TLT5, but it still sticks out too much and may open accidentally while post-holing crusty snow or while bush whacking. Since this is the only buckle holding you in the boot while you're in touring mode, it's quite annoying when it opens -- especially if you're in an awkward situation such as steep snow climbing or rappelling. Solution: swap to a buckle that rides on top of the boot tongue, like Scott Cosmos or Sportiva Spectre
I figured out a few options for the buckle swap mod, and chose one:
1. Modify the OEM buckle system. I tried this. Too fiddly and I didn’t like the bulky buckle riding on top of the tongue.
2. Use buckles from Scott Cosmos. Nice buckles and they’d work, but ladder is riveted on without an easy way of removing and re-attaching.
3. La Sportiva Spectre. Lightweight “Pegasus” buckles with a beautiful low profile. On and off with threaded fasteners, fit perfectly like they were made for the job. Available from La Sportiva as a spare part.

La Sportiva 'Pegasus' buckle. This is the lower (front) buckle from a La Sportiva Spectre boot. It is perfect for this modification. Length is correct, and both ends attach with threaded fasteners.

Install takes all of about 10 minutes per boot. Main challenge is removing the OEM buckle. This requires rotary grinding the head of a rivet inside the boot. To install the Pegasus buckle anchor, you have to enlarge the OEM hole a bit and push in a T-nut. You leave the OEM buckle strap on the boot, and attach the Sportiva buckle with the small square T-nut that comes stock. Take care with matching tools to fasteners. On this pair of TLT6 the buckle ladder was attached with a star drive screw that I first thought was a hex and thus almost stripped out the head socket. Remember Loctite for all fasteners.

Another view, showing the La Sportiva buckle anchor and how nicely the Pegasus buckle rides on top of the boot tongue.

Bonus mod. This is how I do a 'lean lock blocker' so the boots can remain loosely buckled while touring. The small chunk of vinyl tubing is flipped to the outside of the buckle when it's time for downhill mode.
I’m probably going to get asked “Lou, how essential is the buckle mod?” If you don’t climb much without skis, I’d say it’s probably not necessary (though fun!). But if you do a lot of ski alpinism that involves scrambling and snow climbing without skis, or if your skiing involves bashing through a lot of rough vegetation, you’ll find this mod to be valuable.
BONUS PROJECT

TLT5 Mountain, inside side of boot with modified (shortened) buckle ladder installed. I'm not sure what boot this buckle ladder came from, but it has a tab on the end with the fastener hole. Most ladders have blind rivet that's difficult to deal with. I'd think that with access to a variety of dumpster boots you could find a couple of ladders that were kind of like this one.
WildSnow.com publisher emeritus and founder Lou (Louis Dawson) has a 50+ years career in climbing, backcountry skiing and ski mountaineering. He was the first person in history to ski down all 54 Colorado 14,000-foot peaks, has authored numerous books about about backcountry skiing, and has skied from the summit of Denali in Alaska, North America’s highest mountain.