I haven't tried it in the field, only seen in store a few times and read about it a lot since I'm interested in it. I think it's roomy enough but don't kid yourself, it's roomy for its weight, but still small (the SL1). For me, big enough to sit up = enough for a rainy day. I currently use a Sierra Design Clip Flashlight which I love. It has long been the standard tent for light travel. Super strong in the wind too. The reason I'd like a Big Agnes SL1 is to have a smaller and lighter sleeping shelter and use a tarp for rainy days. A tarp is like a huge front porch where you can sip your hot chocolate while watching the rain come down. You can spread your stuff more to make it dry, err... less wet.

Another cool thing is it's freestanding and all mesh so you can set it up quickly without staking it down when the night is windless and buggy. It's not "truly" freestanding. You have to stake down the back or it'll be floppy. From what I've read, it's best to use the guylines for good rain protection (minimum set-up is enough with my SD). My only concern is the light material they use for the floor but I haven't read any complaint or problem. Entering is a bit of work but i can live with that. My other choice was the MSR Hubba (or Hubba bubba?... one person), which has a large side door and thicker fabric but it's barely lighter than my Sierra Design.