I was really disapointed in the red film. The tomatoes didn't do very well at all (although that might be due to other factors, since the other tomatoes (some with silver mulch and some with no mulch at all) didn't do any better. But when I pulled it up this fall, I found that the weeds hadn't been bothered by it at all! They were somewhat physically crushed under it, but creeped out the sides and the holes for the tomato stems. Apparently they got plenty of water and light to thrive. I definitely won't be using that product again.
(Here you can see the red plastic film, and all of the weeds peeking out from the edges and the tomato holes. You can also see how puffed up it is from the weeds growing beneath it.
On either side of that bed are the paths covered in paper feed bags, which are obviously the worse for wear - most of the bags on the right side are completely gone. But the ground where they were is still fairly weed-free, with sure signs of a lot of healthy worm activity.)
(Here you can see the silver mulch (on right), the black plastic mulch (in the foreground on the path), and the black landscape fabric (on the far side of the path). Obviously, the landscape fabric is ruined, while the two plastic mulches look like they could survive another season at least.)
The black plastic mulch did much better - it's a similar weight to the silver plastic mulch, and performed very well, even under a summer's worth of walking/kneeling/wheelbarrow traffic. Again, if I wasn't trying to get away from plastic, I'd use it again.
The feed bags worked fairly well - they're paper, so by this time of year they're pretty faded and bedraggled, but they kept the weeds down very well, and underneath I found quite a lot of worm castings, which I think is encouraging. You do have to make sure to overlap them very well, since they're so narrow the grass in particular will find its way to the light if they're not overlapped enough. I also catch my boots on them a lot, since there are so many loose edges. But they're free, and they're not plastic! Unfortunately, I'm not getting feed in this type of bag anymore, so I'll have to think of something else for next year.
Next summer, I'm thinking of trying paper mulch. Has anyone out there used it? What do you think?