D7100 1.3x crop in sensor vs Crop in Software?

I never shoot once I hit the buffer limit. With the D300s for birds in flight - usually with my 300 f2.8 VR & TC-14E - that gives me three 17 shot bursts in 30 seconds. With the D7100 in 1.25x crop mode (and no TC) I should get four 12 shot bursts (Using the SanDisk Extreme Pro 95MB/s cards). Coupled with the faster autofocus and brighter image this could well be usable.

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Jim