Hej Gunnar,
With the example where only the 296's were used, it is obvious the L-R separtion is very strong in the discant. This is off course because you had the microphones directed very much outside, but it is also a characteristic of all large membrane omni directional microphones. It is also the reason I am preferring small diameter capsules as main pair with this kind of orchestra set-ups. The over directionality of LD omni's force you to compensate with a M(iddle) microphone and a lot of spots to correct the stereo image.
And that is what you have done in your final mix, which sounds actually very nice. I must say I like the sound from the 296 as in your example, but I would not use them as main pair for large and complex set-ups, rather more for small and solo set-ups. I do not think either you can see this microphone as a competitor of the M50 or TLM50 from Neumann. The perspex sphere of the M50 creates a much more stable stereo image, without pulling the high midrange to the Left and Right outer sides of the stereo image.