I also hope the Synapse sticks around - the Synapse 19 is the best general purpose backpack for me. (I've considered the Synapse 25 for travel but I don't think it's big enough to be a good idea.) I lobbied for the Luminary 12 to get a mesh back so I could use it in the summer, but it's going away, so I'll stick with the Synapse 19 for warm-weather use.
I like the clamshell opening and the larger capacities of the Syniks, but I really don't want the extra bulk of the luggage-handle-pass-through on the back. I like the laptop compartment idea but I'm not sure it would be useful in practice for me.