> good alternatives less than 5V

I still think you should consider an LF PIC and 3V supply. One
or more Lithiums in parallel. They aren't the biggest batteries
in the world in mAh, and I realise the Rayovac page concerned
button cells. You may have a monster of a cell

> The circuit is a bait dispenser and will live in the bush, so
> solar is not an option

Thermal pile ? Small windmill (remote of course) ? Can't you
position a solar cell somewhere up a tree and use the battery
at night or back-up on dull days ?

> low drop out regulator

As the circuit is drawing only 290uA, it's well within the capabilities
of the PIC pins to supply that much to other ICs and sensors. If
you do decide to use the 3V option, that eliminates the need for
a regulator. That way you can turn off the entire circuit apart from
the PIC, and only power-up when you have to

> the two diodes would waste less energy

Whatever your PIC uses, the two diodes will consume 15% of
that in heat (assuming a drop from ~6V to ~5V). It doesn't sound
like much in absolute terms (15% of a few uA), but it's the same
difference between 6 years and 5 years. Sounds worse when
you look at it that way

> I see that it has a 0.5uA sleep state

Ideally it has, in practise you may only get reasonably close. On a
bad day, nowhere near it by a factor of 1, however hard you try.

Over-engineer. 5 years is a long time to wait for a flop

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