Ok.
Because of HRM issues (BUG) with the last 4.40 firmware, i downgraded (successfully) my 245M to 4.20
So far, so good... but i discover that there's no way to block/suspend/disable the push of the 4.40 !!!
So, my device is now asking me to do fw upgrade immediatly or ..this night ... no other choice 
Automatic update could be a good idea...but ONLY when the company is reactive to bug fixing...
I can hack the fw to disable update (quite easy) ... but i would like to have the choice as a *normal" user...
Any suggestion ?