For what it's worth, I have routinely used my Peak XV in temps around 7-20 degrees. Even at 7-10 degrees I'm pretty comfortable doing minor sedentary tasks like melting snow.
I bought the peak XV the first year eddie bauer came out with the first ascent line (I think that was 2009? maybe 2010), and I know there have been minor tweaks since then (e.g., strategically placed higher denier fabric panels). However, when I examine my jacket, I actually find the torso area more lofty than the arms. Specifically, the 2nd and 3rd baffle from the top (right where the user's chest and top abs would be) are loft-monsters. I'm not sure if they've redistributed the down placement since my version.
Strange, because the whole point of the peak xv is to be a belay/rest stop jacket...and largely geared to those customers who take guided trips on rainier and take breaks on the hour every hour. I would think that the jacket is designed in a way where the down is distributed to keep the core warm, and NOT too focused on the extremities. The full blown peak XV down suit seems to be the piece geared towards active use, whereas the peak xv is just a simple, throw over all your layers parka. The sizing of the peak xv also appears to support this, as it layers perfectly over all base/mid/shell layers of the corresponding size.
Also, as far as comparisons go, Richard did some testing on various puffys in the past, and rated the Peak XV as on par with the FF Front Point. You can read about it here: http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=24988
Here are some more test results: http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=28404&skip_to_post=236427
Like you, I got my Peak XV at a screaming deal. However, in my research, I recall that the MEC reflex was a much more efficient jacket in terms of warmth/weight, but at the sacrifice of durability. My girlfriend owns the women's MEC reflex, and it's an awesome awesome jacket and perfect for general snow camping and winter activities that don't involve too many points, picks and other fun sharp toys. I'm not sure if that jacket is permanently discontinued or not...I haven't seen it in a while, and I'm not too up to speed on whether it was simply renamed this season etc.
Hope this helps!