"Adwords spenders must be analysing sites for the best ROI"
and within sites, pages and sections / channels. :-)
if the ROAS calls for it, i'll bid discrete elements at many times higher than other elements.
i can think of one campaign where i've got dogs bid at $0.70 and high performers bid at $2.75 (CPC on both). that's nearly a 4x bid range. and, i don't have a range limit, if the ROAS called for it, i'll bid whatever makes sense... cents... ad cents... adsense. :-)
the display conversion optimizer (and traditional conversion optimizer) means i may also put an algorithm in charge of varying my bids for CPA (i weight that setting for AOV, so it's really setting a CPA to achieve a target ROAS)... meaning i unleash the algo to push those bids up automatically where ever it makes sense. the better that algorithm can discern elements (pages, sections, channels), the better it can optimize. hierarchy and segmentation (aka targetability) still reigns supreme.
as the new display conversion optimizer becomes more prevalent in use, site owners using adsense will be affected, the more commercially aligned your traffic, the higher it's quality of traffic, the better it's content, the more you'll make. so while many advertisers (on my end) may not put in the work to push up discrete elemental bids, making this entire post less relevant, overall the spread of the DCO will alleviate that detailed work - to the benefit of the advertiser, and to the high quality, segmented site owners employing adsense.
more on DCO:
towards this same end, you (adsense operators / site owners) control ad sizes displayed, orientation, location, and can even block certain advertisers. this is also not to be ignored. if you knew what ad sizes converted best for us folks on the other end, you'd be thinking constantly about optimizing for that as well. the answer to that question, like the segmentation issues we've been discussing, isn't simple at all. point being, if you're a data driven decision maker (like us on the other end), you should be testing your site to optimize this aspect as well. on the question of whose ads, rest assured G's algorithms are hard at work to optimize the outcome for us both, but the choice of size is yours to make. size is at least as critical as targetability, probably more so. in any case, the DCO will increase both levels of criticality (as it places greater value on discrete element's value). you definitely want to be on the + side of the DCO bidding algorithm's curve. :-)
we are different animals, but we're in the same ecosystem, our needs are aligned in several key ways -- glad we're talking together here.