Things I liked about the Crank Brothers pedals -
1. No issues clipping in any time during ride all winter despite plenty of stepping in snow (same with atac's)
2. Less cleat noise on concrete than spd's (almost silent - though still not quite) (same with atac's)
3. The big, but lightweight platform that looked kinda like a regular pedal was nice (not with atac's - more on this later)
4. Didn't take a lot of force to clip in/out. (same with the atac's)

Reasons I prefer the atac's:

1. Crank Brothers always had kind of a wonky feel to them. I mean - I'm coming from speedplays, I'm used to float, but this felt different. I switched because I was having knee pain and the fitter I went to said they were hard to fit - something about the cleat being able to move back and forth, he said he wouldn't have said anything if I wasn't having knee pain, but he thought it was fine for mountain biking but could be hard on the knees for road biking where you're more locked in a certain position for longer. He said any other pedal might be better for road riding.

After I switched, my knee pain has pretty much entirely gone away. HOWEVER - I also changed EVERYTHING from the fitting - I dramatically changed my pedalling technique based on his advice, got my bike fitted differently, and had the fitter put on the new cleats (in a different position perhaps), so....it probably says absolutely nothing. lol Other people do seem to think they're great and don't suffer from knee pain.

2. Clipped In/Out feel - I never got to the point where I could tell for sure if I was clipped in or out with the Crank Brothers pedals. I just did the motion and wiggled my foot, or overdid it unclipping to make sure I clipped out (though it didn't take a lot of force).

With the ATAC's, I know the exact moment I clip in or out by feel. It's great. I've read a number of other people have had the same experience.

3. Quality / Durability - after about 3 rides I noticed my Crank Brothers pedals had oil/grease on the spindle in the middle of the pedal. Hasn't happened with any of my other pedals (spd's, time atac's, speedplays). You gotta figure - how long is that going to last? I've read that you're supposed to rebuilt them on a semi-regular basis. With other pedals, I just don't have to do that. I've also read some people on here complain about the pedal spindle breaking off while riding - yikes. And frankly, I couldn't even clip in. I had to add the shims they came with to get them to clip in - but then one foot had free float, but the other foot had a little bit of resistance.

My Time ATAC's don't have any leaking grease that I can see. They seem very solid. Nothing messy or weird. They have a reputation for being very reliable as well. The float is great, and even on both pedals. The only flaw I have with them is that I got the Time ROC Atac Carbon's, and while mountain biking I must have slammed the pedal straight onto a rock and the metal plate has a scratch in it and a bit of the plastic on the end of the pedal got bit off (yeah, they're called carbon's but I'm pretty sure the external body I'm talking about is plastic). It doesn't even come close to impacting the operation of the pedal, but it still makes me wonder how they'll hold up to some serious mountain biking and being slammed against rocks and stuff. I've heard the "Aliums" are made completely of metal and are heavier, but might be more durable for being slammed against rocks again and again. None of this probably matters for any other kind of biking though, and again it hit a non-functional (purely plaform) area of the pedal.

4. As I mentioned, the float on the atac's just seem perfect, while it was a little wonky with the Crank Brothers.

The only drawback to the Atac's is that they do sell a platform pedal similar to the Crank Brothers Acids/Mallets called the "Time Control" or "Time Control Z's". But - I ordered those first, and they required more force to clip out of. It wasn't that big of a deal, especially after a couple of rides, my leg provided way more than enough force but when I got the Roc Atac's they had a more "normal" or "easy" release tension - I can't quite imagine it being any easier. They also had a tension adjust so you could make it harder to clip out, which the Control's didn't seem to have.

I know this year they released a new "one side clip in, other side flat pedal" atac as well, if that kind of thing is interesting to you (I don't like that style personally).

I was gonna write a little more, but I gotta go - if you wanted to try any of the Time's that I have you could, I have an extra set of the ROC's and the Control's, though in that case I would need a deposit for the value of the pedal since I'm not trying to get rid of them. :-) They're both within 5 or so rides of brand new though (and haven't taken them mountain biking).

I also wrote about the change in pedals here -
http://forums.mtbr.com/showthread.ph...82#post6911982

And here -
http://www.bikeforums.net/showthread.php?t=636821