I just did 3 days on the AT in the Smokies and ditched my old Platypus 3L hoser with in-line Sawyer filter in favor of a new system. I'd been using the hoser with the in-line filter since 2008 and been using a water bladder in lieu of bottles since probably 1995.
While packing my bag in a last minute desire to try something new I packed two 2L old-style Platypus bladders, my Sawyer Mini filter and a 700ML smart water bottle with the nipple cap. I left the syringe and other Mini accessories at home.
My original plan had been to keep the SmartWater bottle clean and filter directly into it from the Platypus bladders. But one bladder had a good seal with the Mini and the other didn't and so I started to consider all them of them "dirty."
On the trail I kept one bladder filled in the side pocket of my G4 pack and the Smartwater bottle with the Mini attached directly to it filled in the other side pocket. The second platypus bladder would be stashed in another pocket empty until needed at camp. I would drink directly from the bottle through the Mini and would refill it during breaks from the Platypus.
When I got to camp I would fill up both Platypus bladders and the Smartwater bottle and would have enough water for dinner, breakfast and to get on the trail in the morning.
I think the system worked pretty well for me. I don't know that it was actually much lighter than using a water bladder. But I was able to spread the water weight around in my pack better compared to the 3L hoser inside the packs main compartment.
I think I'll stick with this system for the time being.