Here is my 50cents about the gi/no-gi question.
When I started out training martial arts I was attracked to the systems that had no kimono, just because as a young guy I thought this looked more cool.
As my training became more serious I was obliged to wear a gi and so I got comfortable with it. But somehow I was still convinced that it was ridiculous. My thinking was kind of "I can't use those lapel chokes on the street anyway". Mind you, I actually lived in a country where it was raining most of the time and everone wears heavy jackets :)
Nowdays I prefer training with a gi because it brings several advantages.
First it helps in removing sweat from your face when rolling intensively.
Second whenever you are on the top and you trying to choke, you actually need to use your hips to keep your balance. Needless to say that jiu-jitsu is all about hip movement.
Third when fighting with bigger opponents I can control them easily with spider guard and I can slow smaller fighters down the same way.
Fourth, while defending is easier with gi, escaping when caught is much harder, so it improves my defense for the worst possible possitions.
And finally, there are lots of colorful and cool gi for sell these days. Way more fitting than the baggy judo komonos we used to have.
Anyway, I prefer the gi but I am also convinced that you should train without especially in the weeks before a no-gi competition. Or even better. You wear the gi and the rest of your team doesn't :)