Although I still think the A99 with G lenses is a serious force to be reckoned with in terms of IQ, I just simply can't get the kit I want in A-mount. I've expanded my interests to more wildlife as well as aviation so I'm wanting longer reach than my 70-400G. I can't get Sigma long lenses in A-mount leaving Tamron as the only reasonably priced option which I'm not fully convinced about. I haven't considered a 300 f2.8 with converter due to the exorbitant cost of the Sony G and unavailability secondhand. By comparison the C&N equivalents are readily available on eBay at competitive prices.
So after some considerable discussion and research I have decided to start off with the Nikon D7200. Initial impressions are that the camera is very good. Fairly easy user interface with real buttons and dials for quick changes and slightly better noise performance than the A77-2 but not a massive difference. I like the traditional OVF but also see the negatives below. The battery life is very good, possibly around 40% more frames from a battery.
Negatives include the hand grip which I find is a bit too shallow (A77 and A99 have it nailed), and I really miss the EVF for reviewing due to my eyesight. I need reading glasses and then have to fight with the bright daylight and glare on the screen. The other advantage of the EVF is if you grossly over/under expose you can see the effect in the EVF, not so with the OVF. I have inadvertently done this when I took my eyes off the warnings. The max frame rate is "only" 6fps which to be honest is fine for 99.9% of the time but you can adjust the lower rate frame by frame to suit unlike the A77/99.
The 200-500 IQ is superb, I really like it. The VR is excellent, I shot a stationary subject at 1/80th and 410mm (crop sensor so 615mm equivalent) and there was no motion blur at all, I was impressed. Negatives are very slow focus speed and it is impossible to zoom more than half the range without repositioning your hand. My overall impression is not ideal where fast motion needs to be tracked or quick changes in focal length are required but in terms of slower moving or stationary subjects it is extremely good considering the cost. I like it a lot! I did initially try the Sigma 150-600C but wasn't convinced and the zoom rotates the "wrong" way and again needs hand repositioning for full rotation. The Sport model (which I didn't try) is much heavier (tripod essential) and has the same zoom issues.
So far so good but with a few compromises mainly with the reviewing issue. I haven't thrown in the towel with Sony just yet as a reasonably priced A99-2 would tempt me and I have some good lenses to use on it (Minolta 17-35, 28-75, 28-105, 70-200G, 70-300G, 70-400G).
Only a Tamron 16-300 left sadly. Sony cannot supply what I want so rightly or wrongly I've branched out to someone who does and I'm very happy.