I also like the longbow, but with a little use, I found the full length side zip allowed super fast access to anything inside. Not sure about the final version, but I think it might have one very small mesh zipper pocket. The outer compression straps kept everything tight. THere's no "shelf" but the bag can cinch anything to the frame, just like the longbow. I like both the tri and side zip, but prefer the side zip for this bag... it's also a top-loader, just no zip on top - drawstring closure. I usually used a lid from my 6500 bag on the top, but I think they might be providing a smaller lid with the Metcalf. Final version should have a frame extension built into the bag so you can pull the weight over your shoulders if it's fully loaded. It'll be a kick ass bag no doubt about it.
I'll probaby still use my longbow, but just for day trips. Overnighters, I'll be using this one. Don't know when it's going to be available, but I'll be first in line to grab one.