On the other hand it may be the same/similar in which case a 29er specific frame offers no other advantage other than mud clearance. Make sense?
It will be lower, ie comparable to a frame designed for 26″ wheels with 26″ wheels in it.
Look at some pics of 29ers you’ll see the axles are notably higher than the BB, ie the chainstays slope upwards from BB to rear axle. On your 456 they are near horizontal.
I think the mud clearance is no biggie, put a 2.0 mud tyre in when you need it. The question is if you care about the COG being 40mm higher. You might.
I guess pedal strikes won’t be a problem.
@nuke, a friend runs 650b in a C456 very happily, with rigid forks tho he thinks 26″ Fox boingers would work.