Ok lets see if I can answer
Ok lets see if I can answer these questions. In terms of sizing I prefer a really snug fit. I am in the half size group and I go down for mine to fit right because I don't like room between my toes and the end of the shoe. I never have and really you should only need the extra room if you are a heel striker. Landing properly will usually eliminate the forward sliding so a snug shoe is my preference. Based on that I would say to choose your size on how you like your shoe to fit. If you're a half size and like them snug then go down, and if not then go up. As for width they are great so you shouldn't have to worry about fitting there. The soles are designed to compensate for width issues along with the tech bands so the shoe accomodates both narrow and wide feet so you should concern yourself with the length more than anything else.
The 360 is designed fo running and if you look at the sole you see how the durable rubber is plated in specific spots to account for wear. The black part of the sole is soft, very flexible, and not very durable. It wont wear out quick or anything but it's not designed for heavy use. This is how they achieve the flexibility like that of the original ZEM but offer more durability.
When I first tried the H2O my report back to ZEM was that they would make a great daily wear shoe. This is obviously not what they had in mind but in terms of a minimal every use shoe the H2O is the best ZEM offers in my book. The toe cap and heel counter offer great protection from scuffing and bumping and will also add good durability for walking. The sole is also covered more with the durable blown rubber than the 360 is so you don't have the durability issues that you might with the softer 360 sole. Both the 360 and the H2O have a platform sole that is attached to the shoe instead of the way they did it with the original ZEM that had the upper rolled under the sole. In these two models the upper does not make contact with the ground. We did that on purpose ;-) It's a lot more expensive and time consuming in the manufacturing process but necessary for durability sake.
The O2 is sort of designed as a best of both worlds shoe but necessarily great for either of the things I think the H2O and 360 excell at which is walking and running. The O2 makes a great indoor fitness shoe because the sole is flexible, sticky, and covered in the blown rubber. It employs the original style upper that attaches under the sole though. The sole is thicker and the upper is attached a little higher than before so it doesn't contact the ground as much as the original but this in my mind makes is slightly less durable than the other two models. The O2 and 360 both weigh in around 2.5 ozs making them insanely light and the H2O is slightly heavier because of the toe cap and heel counter but not much. I don't have an exact weight on them yet but having had them on my feet I can tell you that the difference is not really noticeable.
Last but not least these are a slip on shoe and you can literally get them off without stopping your run. I purposely tried it to answer this question for you khyricat. I was able to just slow down, catch the heel with my hand, knock them loose, and on the next stride take it off my fore foot. I'm sure it looked awkward and crazy but it answered your question and the answer is it is extremely easy to get them off on the fly!
There are now pages and pics of all three new models on the ZEM website www.zemgear.com 
