Advantages and disadvantages of a TQ

[bmwrider]

I am ready to buy my first TQ but before I do I would like to understand them better, could you folks give me some information.

Ok I have never used a TQ, could someone please give me some advantages and disadvantages of switching from a sleeping bag to a top quilt?

I would like to understand them a little better before shelling out the money for one and finding out its not really right for me.

Ok more info
I am using a hennessy hyperlite with HH supershelter and if needed an HH top cover