Not a rumor - Kubota is having difficulty with the new emissions system on this model. While I don't know the exact issue (because they won't publicly disclose much information about it), I was told it's a problem with the design of the diesel particulate filter system on the tier IV compliant engine.
It was originally scheduled to be released along side the B2650, but this obviously never happened (I've had one on order for close to 4 months now.) I suspect it could be some time before it's finally available.