Although it is somewhat flexy, it isn't necessarily too flexy. It caused me some problems on my old bike in combination with some other issues, but I've never had any issues on my current bike. Shifts just fine, no soft-pedaling needed.
That said, it's probably not worth the money for the weight savings, and the OP wasn't asking about getting one anyway...
I'm running full Rival on both bikes and the only change I think I'll make is getting Red shifters to have zero loss for the rear.
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