Already on this train. Will be careful.
One approach would be to use a smaller than usual aluminum fuel tank (at least for shorter trips). This approach would save weight and make the design more compact. You could have sizes more like the sizes used for alcohol stoves. But the fuel would be lighter and much more energy dense and long-lasting.
For longer trips, you could use sizes more in line with canister stoves -- four and eight ounce for example.
For even longer trips (or longer intervals between refueling opportunities -- you could still use the smaller sizes on the longer trips if you wanted to refuel more often instead of using larger containers -- similar to the alcohol users' approach but more efficient), you could also use the standard Sigg and MSR containers. Or in-between sizes, or larger, depending on trip and refueling intervals.
Ultralight siphon systems would enhance refueling opportunities in some parts of the world. Not always necessary to take but could be very useful for some trips.
Do away with the pump. Use presta valve installed in cap. Very light, simple, serviceable, and reliable.
Use lighter fuel line than MSR uses. Something more like what Primus uses.
Maybe just use the Primus Omni Ti and lighten. (New, smaller, and lighter tank or tanks, for example; presta instead of pump; lighter, simpler stand and housing, etc.)
Or find (or build or adapt) Ti burner for the Borde Bomb design. Lose the brass. Use lightweight line to lightweight tank.