OK - a bit of free thought here, open to any input/opinions. I figured I'd post the debate going on in my head just to see what others might consider doing.
I have my A550, which has been excellent - I have pretty much all the lenses I need currently. My primary photography tends to be birding/wildlife, travel and architecture, low light/high ISO, night shooting, then scenic and landscape, in about that order. I use viewfinder for most of my shooting, but consider live view to be an absolute must for some off-angle shooting and for night tripod work - the A550 solution has been brilliant. My camera is still fine, but just getting on - over 2 years old, over 80K clicks...it's usually around the time I start considering a new body. I'm a JPG shooter most of the time, by choice - I hate post processing and don't like spending time in front of computers, so I like to get as many of my settings right in-camera, and working on exposure/metering while shooting...so JPG engines are very important.
When the A580 came out, it was immediately tempting as a replacement for my A550 - slightly better sensor, slightly better high ISO, adds multistack ISO, adds more focus points and two more cross-point sensors, increases battery life, adds a few more controls, otherwise looks, acts, and feels very much like my A550 (a positive for me).
Now with the A77, I'm torn. Things I love: many more cross-point focus sensors, more focus points, faster focus system, tracking focus likely better, faster burst, quieter, weatherproofed, more controls, more customization, memory banks for stored settings, large body, thick grip, huge resolution at low ISO, minimum ISO 50, better LCD articulation and flexibility. Things I would be worried about compared to A580: battery life much poorer, high ISO not as good, EVF an unknown quotient for me as I've not liked past versions, smaller buffer (or more quickly overwhelmed due to file size), more expensive.
Being that high ISO is very important to me when shooting, I worry that going to the A77 will leave me feeling like a downgrade from the A550, and far from the A580's potential. And I'm worried despite improvements with the EVF that I'm still going to experience eye-strain and lag effects tracking birds. And the battery life is really something that digs on me - I am accustomed to charging my A550 once, and firing off 3,500+ shots over 2-3 days without any worries. Yet I can see some clear advantages to the weatherproofed, superfast body with electronic first curtain shutter and lots of cross AF sensors.
I also have my NEX3 - and have considered upgrading it to the NEX-5N. It's my second body, for lightweight duties and occasional substitute duties. I'm wondering if maybe I could manage to separate in my mind my high ISO shooting needs for low light from my other shooting - maybe getting the A77 to shoot daylight, long exposure, and wildlife/birding, with ISO looking fine to ISO1600...and get used to using the NEX-5N for high ISO handheld work. Downsides to that theory are that the NEX has no fast autofocus lenses, whereas I have my 30mm F1.4 and 50mm F1.7 on my DSLR for those needs...and the NEX has no in-body stabilization, so even using manual fast lenses, I can gain several stops with the DSLR due to the SSS system. Not to mention, the extra cost of upgrading to the A77 and the NEX-5N...it would be much cheaper to grab the A580 and NEX-5N, or even hold onto my NEX-3 for a little longer, since the A580 can do excellent high ISO work.
The A550 JPG engine has been quite good - the A580 seems even better, so no worries there. The noise performance of the 16MP sensor is excellent - not only better at higher ISOs with lower noise, but less intrusive noise, since it's mostly lumi. The biggest issue I have with the A77 is that the noise seems much higher in chroma - and much of that very destructive to fine patterns and detail when removed...leaving blotchy patches. The 14MP and 16MP sensors are virtually free of chroma, no blotchiness, and with a nice, fine grained luminance noise pattern. Even considering the resolution advantage of 24MP which could be downsized to 16MP and compared, I still see much uglier blotchiness and NR smearing at ISO3200 and up, and I shoot there often.
So, there are all the things swimming around in my head. It doesn't help that some of these temptations are hitting me now, with a bit over 2 weeks to go before I'm on a 2-week vacation in Canada and New England - even though I have absolutely no need for any new camera, part of me wants to get one or both before I go.
Open to discussion, opinion, comment, or ridicule!
Sony DSLR-A68 / Sony 18-250mm / Minolta 50mm F1.7 / Tamron 150-600mm / Minolta 300mm F4 APO
Sony A6300 / 18-55mm F3.5-5.6 / 55-210mm F4-6.3 / 10-18mm F4 / 35mm F1.8 / 16mm F2.8 / FE70-200mm F4 G OSS / FE70-300mm F4.5-5.6 G OSS / via manual adapter, lots of Pentax K mount, Konica K/AR mount, and Leica M mount manual lenses