All my spare cash is going to my three season kit at the moment but I'm almost done and then I'll start working on my winter gear. I'm sure I'll still buy an inverted canister stove but it seems that Esbit could save quite a bit of weight for an overnighter. Like you mentioned, probably some trial and error involved with developing the routine.
Boil a couple liters at night and throw into sleeping bag (~3oz fuel)
Melt a liter at lunch (1 oz fuel)
This would only be .5oz heavier than an empty canister.
I don't have any experience with inverted canister stoves to speak to their fuel economy but I suspect that after one or two days, Esbit would no longer save any weight in comparison.
Edit: and thanks for the well wishes!