Photobirding static bird subjects is doable from P&S to the extry level DSLR and no need anymore to mention the high end ones. Depending upon the opportunities for distances and the types of birds, image captures could be made anywhere from 1X zoom to 1260mm equivalent. I have been doing photobirding for more than 3 years and have graduated from usable six image stabilized Panasonic FZ series with up to 420mm reach to some entry level DSLRs.
To me, the most challenging aspect of photobirding is on Birds in Flight (BIF). With the right attitude (another story), practice, opportunities and adequate gears; it could be done from cheaper prosumers (4 MP Panasonic FZ4 samples - http://art4less.smugmug.com/gallery/988010#45645151
and a 7.2 MP Panasonic FZ8 -
) to the entry level KM5D (samples at http://art4less.smugmug.com/gallery/1037506#P-2-9
) and Sony A100 (samples at http://art4less.smugmug.com/gallery/2971384#160721583
Almost went to the Canon side (I catually bought 2 years ago the Canon XT) due to good long focal length lens line up esp. on the used ones but my meager A-mount lenses, unsteady budget and some hopes from Sony made me stay for a while. When the A700 was announced, only two main features attracted me - the supposedly faster AF and better burst performances. Those were the two items I was mostly looking at for increasing fun factor level as I am still 100% jpg and handheld. Do I need high ISO? Only for documentation purposes like for first/rare sighting if there are no more options. IMO, bird images with adequate light would always beat images from little or no light at all. Am I concerned about IQ? Not much really as most cameras have enough in-camera settings to play with the optimum IQ and if not enough, I have several PS plug-ins that could remedy the situation. I am from old basic school just concentrating on relationship of shutter, aperture and ISO to get most what I want - capture motion, increase shutter speed or sensor sensitivity; not enough light but can't sacrifice speed, increase ISO or use exposure compensation; not enough light but can sacrifice speed (thanks for the SSS), slow shutter or open up arperture. I can live with those settings and features as long as AF is very good.
With the above background, the following 3 part posts hopes to give some idea on photobirders wanting to consider the A700. I used my Sigma 50-500mm DG (aka Bigma) for all the mentioned shots and majority in 500mm (750mm equivalent). Typical settings: shutter priority or manual, 1/1250 - 1/2000, f6.3 - f10, wide AF mostly for fast image acquisition, AWB, ISO200-ISO400 mostly, vivid with +2 sharpness mostly. Images were mostly cropped and some PP - highlight/shadow or level adjust in PSCS3, a bit of noise reduction with Digial GEM plug-in and a bit of sharpening with Focus Magoc plug-in or smart sharpen in PSCS3. Note that the images prepared in a CRT and appeared a bit over sharpened and over saturated in my LCD.
Enjoy my findings below,