Generally speaking, light is more comfortable but less durable and easier to grip. Heavy is the opposite: less comfortable but more durable and harder for your opponent to grip.
Also, wearing a heavy gi in the summer will feel like you're wearing a backpack when its full of sweat
the reasons above are why I wish somebody would create a light/summer weight gi with a Howard-type horse collar
To be honest, I didn't notice that I get choked more when I wear a light gi, I'm good at defending gi chokes, and once they sink in it doesn't matter if I'm wearing ultra thin or thick collar, I have to tap. Mind you, the stiffest collar I've tried is on my adidas rio comp.I hate hearing about how much easier it is for an opponent to manipulate and choke you with a lighter collar. What the hell do we train for?
The old generation Atama ultra-lite (the one with yellow and green on the shoulders) is the closest I've seen to that. Great collar, very light, but not sloppy. Probably my favorite gi after having the skirt shortened.
It's bad but not that bad, you get used to it after some time. I rather feel like I have a backpack on my back then the feeling of getting beat in every sparring match because my gi was easily manipulated.
Usually summer gi's are soft and bendable and the collar is too soft so your sparring buddy will have an easy time grabbing it and trying a choke on you. I hate getting thrown around like a rag doll with a real soft summer gi.
Wear your heavy gi Nov-Apr and your light gi May-Oct and call it a day.
I hate hearing about how much easier it is for an opponent to manipulate and choke you with a lighter collar. What the hell do we train for?
If you have good posture it's going to be hell for your partner to choke you, regardless of what kind of gi you're wearing. If you have a good base and good transitions, it's going to be hell for your partner to sweep you, no matter how easy he can grip on to you.