The boots I had before these were the Nike SFB's for about 1 year 7 months.
Weight: Pretty light, just about the same as the Nike SFB's
Tread: Better than the SFB's but the soles aren't as flexible. They seem to be made of a bit tougher material. I've only had these a month so time will tell
Comfort: Not as comfortable out of the box as the SFB's were but I definitely like the lacing system better, the bottom laces stay tight, while the upper laces are like the upper laces of the SFB's. The top of the heel cup on the C4's were bothering me a bit the first 2 weeks, especially if I happened to wear a thin pair of socks that day.
I've had the C4's for three months now. Working 12 hours security shifts and wore them for our predeployment training. Really comfortable and lightweight. The soles DO NOT protect you from anything. During patrolling in the El Paso desert, I got SEVERAL long ass thorns directly into the bottom of my foot.
Besides that, tread held up nicely, laces stay tight (I loop them behind and tuck a loop/end into each side of the boot), and I have no issues with breathability in humid ass Africa. Overall, good boot for the price and they are holding up fairly well and I go through boots pretty fast.