I have TIME ATAC Alium pedals, the cheapest ATAC pedal you can get but with just the same technology as the carbon version. They are 1g heavier than Shimano 515s and much, much better
than any SPD-system, especially if you are riding muddy trails a lot. They leave the foot much more freedom than SPDs which is very good for your knees and there are no accidental releases at all. There
is only one thing to remember when using these: the heel leads if you want to unclip. Money well spent.