I’ve had both (and a Soul) and they were both very good, but in short it’s the C456 I kept. In long…
Ignore the Bikeradar review, it’s absolutely demented. The C456’s not the stiffest frame I’ve ever ridden so how it stopped them from riding down rocky descents without destroying their arms, when stiffer frames like Chameleons and Sovs don’t… Personally I reckon the fork was broken and they were too keen to talk about the frame to register that. But anyway, it’s utter cobblers however it happened.
The BFe is stiffer, and obviously heavier. The geometry’s better IMO- subjective o’course but they descent similiarly while the C456 as standard climbs worse. The BFe also just feels that bit more inspiring when you jump on- the C456 will do everything the BFe did for me, but the BFe felt like it wanted to, if you know what I mean. Also the BFe is extremely well finished while the C456, well, it isn’t. Scratches easily and really feels like there’s no attention to detail, stuff like the cable guides being in the wrong place on the top tube etc.
But the downsides… Weight, obviously. And for me, stiffness- I don’t really like as stiff rear end on a bike, I always find a bit of compliance means extra control and speed, and the C456 works very well from that point of view for me. (comfort isn’t an issue on either bike)
And flexibility- I’ve stuck a 2 degree head angle reducer in mine which makes it a bit ragley-ish and makes it a very confident descender without making it any worse on the ups.
On that pliant rear end… Some people might call it bendy, or soft for pedalling. I don’t but that’s a matter of taste.
But they’re very close, and I’d own either again (or a Soul more likely).