Poncho in Colorado High Country?

Not rediculous at all. You will want some type of elastic cord around your waist to keep the flapping at a minimum, but a poncho will prove more comfortable that a rain jacket and rain pants.

Monsoon season is warm and humid. My experience with a rain suit is to be wetter on the inside than the rain on the outside. Experience with a poncho is that I stay dryer due to better ventilation.

I hike in the wet North East.

I prefer a poncho style rain jacket, but I tend to use a short version often called a cape. I combine it with my ground cloth worn as a rain skirt if it is really pouring.

I've had problems with long ponchos hanging up on stuff and they can be a real problem on scrambles.

I also wear a hooded windshirt under my cape and remove the cape unless the rain is heavy. A little dampness isn't an issue with the right layers underneath a windshirt.

Normally, to most people I would say that a rain jacket and pants is better. The storms here are irregular, but they can be intense for the brief time they last and getting wet at 10,000 feet is no joke.

But if you like your poncho and- more importantly- it works for you in the PACIFIC NORTHWEST then, hell, I imagine you'll be fine. The rain here isn't as bad as what you've already weathered.

Monsoon season, up here, is not that warm. It's warm when it's sunny, but when storms roll in, it's quite cold and temperatures can drop 20 degrees or more, very quickly.

I prefer rain jacket/skirt and sometimes pants. I spend a lot of time summiting mountains, jumping across talus fields and scrambling along ridgelines, so a poncho is, by nature, a very bad choice for me. I try to get off of ridgelines and summits before storms roll in, but sometimes that isn't always possible, so having upper body rain protection is really important.

Wearing softshell pants gives me the protection I need on my legs until I can get away from exposed terrain (a high priority in storms). I bring a skirt (~1oz), since I only need lower leg protection when I'm on trails or tundra in sustained or heavy rain. I'm certainly not on exposed terrain, then, as it's dangerous for multiple reasons!

I bring my rain pants on day trips or when there's a possibility of not getting enough sun to dry off each day (very very rare in CO).

When it's too warm for softshell pants, I wear running shorts, wind pants and a rain skirt. However, it's rarely too warm for softshell pants at the higher elevations. That's more for the foothills, the desert, or the Lost Creek Wilderness area.