The a99 is a trade-off regarding build 'strength', let's call it. It has a solid metal body with lightish battery and card doors. I find it a good compromise, as weight is a very important use factor. It cannot fairly be called flimsy, except by comparison to a Fuji GW690 maybe.
Peaking is best used for determining DOF or on occasions gauging the focus plane with fast lenses, for high contrast focus 'targets'. Magnification via EVF has no peer in camera land as far as I am concerned, and can/do demonstrate it, for manual focus lenses.
'how impressed I was with the A900, but this time it feels like Sony's heart isn't really in it any more.'
I agree, Sony are now thinking with their heads not their hearts, and the hangover Minolta days are now in the past for their full frame efforts. The a900 now feels like a basic solid box, and a market failure to boot, many users downgrading it for lacking modern niceties such as video and an LCD. I am glad so many still like them, mine will be for sale very soon.
The a99 is like a scalpel at work, fast and so accurate - very results oriented. I have not mentioned the great metering and WB before, these are much better also. My rather unkind a900 remarks come from years of guesswork as a manual focus user, for both focusing and metering with alt lenses. The irony is that it took an SOA highly electronic camera to realise the best manual focus experience for these crucial aspects of imaging.
I do think DK, MR et al are trying hard to ignore the benefits of EVF, so I see them as unhelpful Luddites. Criticism pours forth from their keyboards rather than advice or explanation or usage preferences. They seem not to realise that many/most of their readers: (i) have never used a DSLR/SLR OVF, the market being dominated by APS-C and smaller formats, many using EVFs; and (ii) are fully aware how to live with and get the best from EVFs. You get the sense of a sermon from the mount approach, issued from on high.
'the focusing and review functionality wasn't overwhelmingly good.'
Using a manual focus lens? Did you find the button for magnification, carsten, or even use it in the EVF? Use review in the EVF? It's the extra magnification right in front of the viewing eye that the EVF affords that makes it so much more effective than any parallel viewing using the (albeit excellent) LCD.
Agree the camera needs time and understanding to set up for personal usage, it is the most highly customisable camera I have ever used. Like all good interfaces, it provides a number of ways to achieve the same goal, to cater for all user categories from curious shop tyre kickers through to to hard core users. Like the best art forms, modern cameras demand input and knowledge from their customers.