well, new head gaskets, new valley gasket...
... and it's still using coolant.
not at a huge rate, but faster than I'd prefer bearing in mind that 25% of it costs money.
When I had the heads off, I didn't investigate 'em very thoroughly, but all pots looked pretty similar - in particular, there was nothing obviously different about the colour or deposits on any one; I'd probably have noticed and thought "hang on..."
so, bearing in mind that I can't see any obvious leaks, is it possible for a head to be dodgy in such a way that water from the jacket escapes through the engine in such a way that it's not visible as contamination in the oil and causes no obvious problems with running. I've not actually done a compression test yet, but it runs nice and smooth at idle now it's had new head gaskets, so one pot, for example, isn't a long way down on compression.
hard to get a definitive answer for the rate of coolant loss, but I'd say that it's about a litre every 100+ miles, which is way more than it should be, but not really enough to be obvious. I'm going to try running it unpressurised and see if it leaks faster, slower, whatever over the next day or 3.