How do you feel about center zip sleeping bags?

I finally decided, and just purchased the Long REI Magma Trail Quilt 30.

I used a no-zip, hoodless golite feather-lite, although I tend to grab my quilt more often these days.

I see that quilts are really popular but for me the cost in some weight and bulk of a zipper is easily offset by the protection against cold and that enhanced temp range. For me it is the worst to be cold overnight on the trail.

After 8 years or so with a quilt, I'm not sure I believe this any longer. At the very least, I think it is fair to say that quilts are more prone to user error than bags. If you have a really good pad attachment system and use it properly, I guess you can completely seal out drafts, but I've never been entirely successful. I love quilts for their weight and venting possibilities, but I've reached the point where if I expect the temperature to drop below about 35 degrees, I'm going with a bag.

driftwoody , as I'm sure you know, the challenges of eliminating drafts with a quilt don't really exist in a hammock, partly because your underside is wrapped in an underquilt, as opposed to lying flat on a pad. Much less coverage is needed in a hammock, and it tucks more easily underneath you. I think you are really going to enjoy your quilt.  Assuming you have a quality underquilt, you are going to be completely wrapped in a cloud of down.  

Thanks for the feedback everyone. I will look closer at the numbers regarding weight and bulk of bag vs quilt. I think it clearly has two forks here; ground/pad sleeping and hammock. I think that for hammock the case for just a top quilt is very strong. For ground sleeping a little more gray. I have been hammocking mostly recently.

The boost in warmth I like to know I have with me with a bag has other reasons beyond just low air temperature. There has been times when I have been exhausted and possibly dehydrated and possibly underfed when in an air temp that I would normally be warm I need the extra warmth from not making heat as well. The added warmth also helps my muscles recover overnight I think.

And on a final note a large number of nights I am out using my bag as a quilt. Actually in the summer a lot of times nothing on top. So maybe a quilt for me but I still really hate the risk being cold overnight.

This is an accurate assessment, in my opinion. But given that you are spending most of your time in a hammock, and often use your sleeping bag as a quilt when sleeping on the ground, I think you would be very happy if you added a quilt to your quiver. The Magma sounds like a great quilt, an even less expensive option would be a Hammock Gear Economy Burrow. You can customize this quilt with color, width, length, and overstuff. This is a great cottage gear company.