Dang dude, we're gonna have to have a convention up in the Sierra this summer! LOL
Here's my version (essentially using your same exact dimensions), except I used 2" baffles & the full amount of 12oz from the kit:
I figured I'd rather have 6oz extra of 900FP down than have to carry extra [non-loft] clothing. Either way, if you're over 10k, even in the summer, you know you can freeze your butt off if/when the temps go below 30.
I find it interesting that our lofts are perfectly in proportion to the amount of down fill. Here's what 12oz gets you with identical dimensions:
My quilt came in @ 17.5 oz - our (very slight) weight difference, other than the 6oz of down, is probably due to my use of only buttons and no top tie. The other primary difference, but probably has no effect on weight, is the use of Karo baffles. I really like the way this has turned out, especially since I can shift down to/from specific areas.
If anyone is reading the full details of my construction, here's a link: http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=62019&skip_to_post=530355#530355
Last, but not least, I'm impressed with the compressibility. I'm putting the finishing touches on a new pack designed specifically around my BV450, this quilt and my (cut-down) Ridgerest. I'm going to post a full story, but here's a pic of how I sized out the dimensions of my myog (filled) stuff sack in order to derive the pack dimensions.
Note that I want the bear can in the middle of the pack (the bag on the left gets shoved to the bottom - clothes, extra go on top of the can to the right), not hanging outside, off the bottom, or some other potentially uncomfortable configuration.