That trick is fine in emergencies but I avoid it at other times now. I used to shift without the clutch all the time just for fun, even in my DSM which I knew was tempting fate given the DSM tranny reputation. One day I was being particularly lazy and inattentive and I didn't hold it against the next gear firmly enough. When the RPM matched up I only pushed the lever in halfway and it was the most horrible grinding gear gnashing experience I've ever had. After that I couldn't flat shift into third above 6000rpm- one bad clutchless shift screwed up the synchro in my rebuilt trans.

So yeah, great for emergencies, but I'd avoid it at other times unless you just don't care about the car, in which case it's a lot of fun to play around with. Stop and go traffic is no fun- although technically your car becomes a "hybrid" as you are constantly cranking the starter in gear to get the car moving again.