My Arc AT is the long version with 1 oz. of down overfill, and I paired it with a Skaha Plus, also with 1 oz. of overfill. I was sleeping on a GG 1/8" ThinLite and BPL Torsolite. My ULA COnduit was under my legs.
I can already tell, after only one night, that this mix is going to be so versatile and be my standard for all 3 season outings (though, I'm definitely going to pick up a Kooka Bay inflatable pad).
I want to say we got down to the low 40's Saturday night and I had NO cold spots, so drafts, etc. I was very toasty, and did not wear the hood on the Skaha. I also didn't zip it up.
The whole set up was a breeze to set up. Definitely a keeper!
As for the comments about the Monk, yeah, it's a fairly "spartan" set up, but I'm 6'1" and had no problems getting under it and felt sufficiently covered. Moreover, I carry a ULA Rainwrap and can fashion a "door" at the front (with a slightly different pitch from the shown above) and have full coverage. The only caveat to that would be horizontal wind driven rain, which we don't see a whole lot of in the Mid-Atlantic.
Feel free to post any other questions. I can't say enough good things about the set up!