merge replication, SQL2014 and the new cardinality estimator

Hi all,

I have just upgraded our publisher from SQL2008 to SQL2014.  We have 500 odd subscribers who sync on demand to SQL Express 2008.

Since then it seems the amount of blocking on the database between subscribers has increased , also some message in the sync log appearing more regularly,

The process is waiting for a response from the query '{?=call dbo.MSmerge_ins_sp_DEAC08624FE6482B7546B0DC89494557_batch ('89ECBC0F-DC97-4AF5-81AC-3A88CE22C620',?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?'

The process is waiting for a response from the query '{call sys.sp_MSenumchanges_notbelongtopartition(?,?,?,?,?,?,?,?,0)}'

 I am wondering if the new cardinality estimator (which is enabled) , could be the cause of the issue, in causing some bad access paths to be taken.

Has anyone any experience of this being the case ?  Are there any options to address this , other than disabling the new CE via a trace flag ?

Thanks

BTTF