Caveat: I have no experience with the model mentioned.
My experience with more industrial-strength panels is that you need prolonged periods (6+ hours)of direct sunlight and even then that may not be enough depending on how often you are using the charged device and the condition of the batteries. Here in Afghanistan that usually isn't an issue, but I can't see a portable solar panel doing much for you, especially out of the desert or on devices which you constantly use (like a radio). One other consideration: Your charger's cables are maybe 3-4 feet? Now you need direct sunlight AND you have to keep your device out of direct sunlight, especially civilian products.
Looking at the specs for the various Brunton models out there, the 26W version will clock in around $550 with the lower end models considerably cheaper.....but the output is reduced to 4-6 watts which is okay for some devices like an iPod or cell phone if you have enough time.
Maybe the technology is out there, but my experiences aren't terribly positive with solar panel/ chargers in general. An emergency where you have a bunch of direct daylight? That would work, but heavy use of a device where a lot of sun isn't possible? I don't think a solar charger will keep up.
Your best bet is to invest in a vehicle solar charger to keep the vehicle battery charged (reverse charges through the 12v output) and then run an inverter off of the vehicle battery. My vehicle charger is a 12"x12" and will keep a 12v battery charged with only about 3-4 hours of direct sun, or 8 hours of diffuse sun.
Mine works great in the VW - it kept 5 cells phones charged during the course of 2 weeks and ran other electronics as well, I haven't tried it in the other vehicles.
Thanks for the input, I'm mostly interested in something I can use while hunting here in AZ where sunlight is plentiful. Mostly to power my phone and perhaps a radio, GPS and only when I can't get back to my truck.
Radio and GPS I would find a 12v compatible, rechargable battery charger. Use that to charge AA's to power them with, that way you could leave the panel in a good spot where it'll get good sun.
TBH the rollup panels are a better deal for no other reason than you can toss it over a rock and let it get pretty good sun throughout the day, you can have panels facing the sun at pretty much all times with no effort. Expensive though.