I could not make up my mind either, so I got the synthetic thermawrap(250g) for 3 season/wet climate and the Light Alpine Down(310g) for winter/alpine use. Both jackets will evidently last for decades given my infrequent use. My only other torso insulation is an REI fleece jacket.
One synthetic, one down, one fleece. Used singly, or layered. Wish I had understood this simple concept before I wasted a lot of money.
But Chad, since your bags are both down, a case could be made for buying the synthetic thermawrap, incase your bag gets soaked with condensation or liquid water.
I also bought two bags to make a 'system', in my case a #7 and a #3. By the way, putting your #5 INSIDE your #2 to make one huge bag should keep you alive down to -31'C, and comfortable at -15'C.(calculated by combining fill weights) Let us all know if you test that out? ;)
Oh, and this pic is to tempt Ben..