Some interesting posts, but for now I'll concentrate on trying to answer eleven's question.

My view of these patterns is quite simple; for a SdC type pattern there are overlapping ANSs that combine to give a 2-sector Naked Set and for this pattern there are two overlapping AHSs that combine to give a 2-sector Hidden Set.

For both situations the combined digit and cell counts must obviously balance, and care must be taken to ensure that the counts for each digit in the combined pattern are forced. Usually this will mean each digit must occur once in the pattern, but there are other possibilities where individual digits or perhaps one or other of them must occur twice. I thought that the rules governing any second instances would be straightforward but as I was writing this, I realised I missed a case which makes them more complicated. That said however, when any potential 2-sector set is found it's easy enough to see how many member digits must be true in the combined cells.

I can't understand when everyone seems to be so comfortable with ANSs they don’t feel equally comfortable with AHSs. I certainly find them easier to spot*. When two AHSs overlap, each one needs one more digit to be restricted to the cell set to become fully locked, and when that digit must come from the locked members in the other AHS, there is a hit.

My approach is to look for AHSs in the boxes. For each one I identify I then check how the digits that aren't locked in that set are locked in the intersecting rows and columns. It doesn't take much practice to recognise the cases worth investigating.

As I don’t rely on a solver program I can't quickly run through a batch of puzzles looking for them, so my experiences are limited. So far it seems they often occur in conjunction with 2 sector ANS (as in the original puzzle in this thread), and the stacks and tiers worth investigating first are those that contain bivalue cells. They also seem to be rarer than 2 sector ANSs.

*To help me, as I switch between focus digits, my spreadsheet shows me the other digits that a) always, b) sometimes, and c) never occur with the focus digit in each house. It's not a comprehensive system, but it takes some of the drudgery out of finding ANS/AHS partitions.