I still tell if there are signs of sex yet. If at all possible, check your camera for a "Macro" setting, which lets you take picture really close up of things. In one of your pictures it looks like it might be a hermi, but without getting closer, I can't tell for sure. The higher up on the plants you look, the easier it will be to tell. By the 6th or 7th node, you should be able to tell.

The plant in the first picture: it looks like nute burn. Stop using the nutrients immediately, and just flush the nutes out with water. That's my guess, since you aren't using CFLs or anything to burn them.

Regardless, your other plants look great. Very healthy. They may be a bit yellow-ish....check some of the other threads to see what that means (i.e. too much K, Ph, etc.). I'm no expert by any means, of course.

I really wouldn't worry about trying to sex them if they are being shy Just keep doing what you're doing and eventually you'll be able to tell. It took 2 months for one of my grows to sex the plants...I just couldn't tell.

Keep it going!