I converted to hanging a short time ago. Not much experience yet, but.... I just had a chance to add up the weight of the hammock gear and compare it to the tent gear I was carrying. I thought you all might be interested in some concrete data. Here's how it came out:

Tent (MSR Hubba-Hubba) 68.8 oz (at 6'6" I needed a 2-man tent)
Bag (MH Switch Tall) 56.0 oz
Pad (Thermarest) 15.0 oz
Total: 139.8 oz or 8.73 pounds

Hammock (WB BB Double 1.7) - 40 oz
Tarp (Mamajamba Silnylon) - 15.25 oz
Under Quilt (Hammock Gear 3/4) - 15.7
Quilt (Tech Blanket) - 19.02
Total: 89.97 oz - 5.62 lbs

Difference: 3.11 lbs

When it's cold enough to take the bag instead of the tech blanket, the gap narrows - adding back the difference of 36.08 oz or 2.25 lbs to make 7.87 lbs.