I have a set of the titanium out-dry rain pants and rain jacket. They work very well and don't soak through. I don't think they are as breathable due to the more rubbery fabric. I'll take more waterproof but less breathable over breathable but will saturate when I'm in the mountains. As far as durability goes, a buddy had his on a rainy moose hunt last year and wore them nearly all day every day with no issues.
I have jacket but not pants. It won't wet out that's for sure. It breath well enough but I'd still prefer it to have pit zips. Durability wise its pretty tough stuff. Biggest negative is color choices.
The diamond shell specs on their site say it has 2-way underarm venting (I am thinking pit zips?), along with some sort of sweat wicking liner (EVAP). These features are not on their lower level shells. I keep hoping some one on this site will do a side by side comparison with the latest and greatest from KUIU and First Lite. If not, I am thinking I will breakdown and get this jacket, maybe this years Christmas present to myself.