First time I REALLY put the Dariens to the test (pants and jacket) was on an 800 mile ride down to Deal's Gap. We went throught some serious gully-washers that went on for hours.
The Dariens leaked, both of them. Right through the zippers. The pants would leak right at the crotch and the jacket through the zip.
I have had other rain gear that didn't leak. But they weren't armored. I've ridden many miles in downpours in North Face goretex mountain pants and jacket with no leaks--but they had to go OVER the protective gear. Cheaper, non-gore-tex rain gear also worked better.
You'll need to use seam sealer and Nik Wax to improve the Dariens' water-proofness. It does help.
That said, I REALLY like the Dariens. Light rain, shorter bursts, they do just fine. It was hours and hours of hard, driving, gully-washer rain that got them to leak. Just I've been in similar conditions with other stuff without those results. What they give it is a super-versatile riding system you can use year-round, depending on what you put under them.
They are not the best rain-gear--they are only OK. They just do SO many other things so well I'm willing to put up with them not being perfect in the rain.