I've been using the Switch Designs boot bag for most of a season now and I have to say it's really clever. I have relatively small boots, so I've always been able to fit them into a 24l backpack to keep in my hand luggage (European budget airlines do not let you carry boots loose in addition to a bag), but the Switch bag has been a revelation nonetheless, allowing me to travel with more gear than before, more conveniently. It avoids the situation of crushing my laptop against my boots courtesy of the separate padded boot compartments and the 'switch' feature (from backpack to tote) means it will slot neatly into pretty much any space when you need to stow it.
Typically, I pack mine with my boots, laptop, a magazine, a book, a gopro+grip, water bottle, helmet, a jacket for when I get to the mountains and it gets cold, plus some other bits. No other bag I've tried has allowed me to carry that much and still take it onboard (on Easyjet) as hand luggage. Technically the bag is actually slightly larger than Easyjet's restriction but in 10+ flights, I've never been questioned with it on my back.
I do find myself using it in backpack mode 90% of the time though. The tote mode is comfortable and balances weight surprisingly well (given that both boots are at one end), but I usually have a big ski bag with me so it's nice to have my other bag on my back, out of the way.
As a backpack, there are some small inconveniences. The bag is pretty wide, so if you're walking about in tight city spaces, you are going to piss off other people by bumping them if you're not extremely careful. A cross-chest strap would also be nice to keep the bag more stable, especially for skiing as it is a bit unwieldy to actually ski with. But that's not the main priority with what is essentially luggage rather than a daily on hill bag in my mind. I find it comfortable to wear and the convenience of having everything I need in my backpack has been a real bonus. Sidenote: This also makes the perfect day bag for a trip to the slopes (indoor in my case) as I can get everything I need for a day of shred inside.
All in all, I think the Switch Boot Bag is a great piece of product design by a skier thinking outside of the box. For me it does for boot bags what The Douchebag did for ski bags, it just makes sense. - Twig