It's always interesting to see how minimal people can get, something I aspire to as well. I think though that the Synapse is definitely too small even for most minimalists. I was debating doing a 10-day trip to Russia this winter using just the Smart Alec, but I've decided against it (mainly because I ended up also ordering a Tristar!). I do think 26 liters is doable for trips of unlimited duration, but it requires extreme discipline as well as nightly bathroom sink washing.
When traveling I much prefer to do actual laundry in a laundromat once a week, so I try to get at least 6 days of clothes out of my bag. This is relatively easy if you re-wear button down shirts (with an ultralight undershirt underneath) as well as wearing pants for 4-7 days at a time. I typically travel with two pairs of jeans (once which I wear), 3-4 lightweight synthetic button down shirts, and then 6-7 undershirts, 6-7 pairs of underwear, and 6-7 pairs of socks. I know jeans and multiple items are for some reason taboo in the travel crowd. But in much of the world jeans fit in better than the alternatives, and thin jeans don't have to be super thick. Also I love putting on clean socks and underwear that smell nice after being machine washed, and considering they take up very little space, I have no issue bringing many pairs.
Here's the gear list of a guy who is taking a year-long round-the-world trip with only a Smart Alec:
Gear List - 12 Month Round the World Trip