You're also going to spend $828.00 + shipping and handling for the CHEAPEST possible combo of pants and a jacket. I'm not advocating for buying First Drop, per se, but I'm just saying that you can get much more bang for your buck with a more "generic" brand of outerwear than with Trew. You can spend $300-ish on a Gore-Tex jacket that is probably more waterproof than Trew's by a fair margin, just you won't have the brand name.
But to think about this from a realistic standpoint, I wouldn't buy that $300 Gore-Tex jacket, because I probably am not going to notice a huge difference between wearing that and any other jacket I pick up that is reasonably waterproof. In my opinion, if it's absolutely pouring rain, you're going to be miserable regardless, and paying $450-500 on a Trew jacket isn't going to change that.
So in my opinion, buy whatever you want. I have a pair of Saga pants from two years ago, and an 8k (i believe) jacket from this year. I ski at Snoqualmie and elsewhere in the PNW, and don't remember being extremely bothered by the rain. But if you want to spend upwards of $800 on a Trew setup, go for it, or spend half of that money on a First Drop suit. From my perspective, you will not notice a difference.