In reply to top cat:
> 1. You can't get into the binding in deep snow. ('Cos you can't see the tiddly pins)
I've not noticed this problem, but I had already worked out the solution to (2) by the time I got to tour in deeper, softer snow.
> 2. You can't get into the binding on hard ice on a steep slope. ('Cos the fiddly pins need pressure to activate and the ski slips sideways)
Position the toe of your boot, by hand if necessary, and yank up the touring lever to lock yourself in instead of trying to stomp down. It'll be much easier to click the heel in once there's no risk of the toe popping out. Once clicked in at the toe, slide the ski back and forth a bit to make sure any ice in the boot toe holes has been squished out.
> 3. You can't get into the binding when it is balled up
Never had this problem, for whatever reason.
> 4. When iced up (frequently) very difficulty to switch modes
The toe's never iced up for me, for whatever reason. I see other folks suggest using something pointy but non-metallic like a golf-tee for dealing with this situation. The heel has never iced up for me at all.
I've seen both Marker and Fritschi touring bindings ice up in touring mode making it quite awkward to get back into ski mode. The owners have threatened to pee on the bindings to get them to defrost, but happily that's never been required in practise.
> 5. DIN settings compromised when heel unit is iced up.
No idea what this means.
> 6. Fitting ski brakes makes balling up MUCH worse.
I use brakes and have had no problems with balling up, as above...
> 7. Finally, you damage your shoulder as you hurl them over the cornice and into the abyss in sheer rage and your tears of frustration freeze and you can't read the map.
I've seen one dynafitted ski pre-release and twiddle the heel into touring mode, letting it slide off into a crevasse, which was entertaining.
I've also seen a guy with dynafits competently mounted to dynafit skis using some other brand of boots and have baffling pre-release problems even in tour mode due to out-of-spec toe fittings... not something you can spot in the shop! Dynafits are very sensitive to imperfect components and mounting, which sucks, but you only need to make sure they work together once (and preferably before you go on a long tour).
You should set em up and then spend a day or two in icy bumps to make sure you've got the release values right and that you've had a chance to practise clicking back in on an inconvenient slope. They're not quite as click-and-forget as other bindings are.