Ive got a Synapse 19, bought shortly before the 25 was announced. I love the bag, but I do find it a little small, especially when I need to carry my camera and a jacket with my Nalgene, which takes up most of the interior space.
As a 6 foot tall male, the Synapse 25 would probably fit me a bit better along with giving me that extra space to handle my fiancee's cargo as well as mine. The real question is if I decide to get a 25, do I sell the 19 to finance it or pass it on to my fiancee, who probably wouldnt appreciate me buying another expensive bag when we are trying to fund a wedding.
Do you prefer to sell your bags when you move on, or pass them down into the family?