The sleeping bag/pad vs. UQ/TQ decision has a lot to do with where and how you use your set-up.
Cold Cold Cold - Shug's undisputed expertise shows how to extreme cold winter camp (his videos are great). In this kind of cold, you deal with condensation and heat retention - outside moisture is in frozen solid state and dry loft retains your heat. TQ/UQs of down provide loft and pack down well. Great for far North winters and desert use as well as summer backpacking.
Cool damp as in mid Eastern US coastal areas - here you deal with down TQ/UQs getting damp and loosing effectiveness from absorbing outside moisture and inside condensation. This is accumulative over several nights and requires airing/drying out on sunny days - ok in warmer weather but dangerous in 32 degree wet snow. Synthetic TQ/UQ or sleeping bags with pads (and wool/fleece blankets) work better in cool damp environment.
Main point is that Air flow robs your loft of heat (TQ/UQ/Sleeping bag) - I've slept warmer on 25 degree nights with no wind than on 60 degree nights with a cold wind. The issue is how to block the wind without retaining inside moisture - condensation. Hammock Socks and enclosed tarps are two common methods to do this. Pads also help here by blocking the wind from underneath. I've used a rip-stop tarp pulled in like a loose burrito wrapper on windy dry nights. Windy and rain would be sock weather. Best of both would be to use both - a wind sock and a tarp. Just Jeff has a nice pattern I used to make a soft tyvek sock to block wind and overspray, along with my tarp.
So area/weather determine what is best for you. There is no one solution for every condition.
This is the attractive part of hammocking that HF supports so well - no matter what you currently have and know, there is lots more to try and learn to improve your individual situation. Just have fun and get out there and enjoy it in good weather. Learn and experiment when you can't get out. This is also my excuse to get more neat stuff:>)