Forest River has reported that perhaps a fix to the vibration problem may have been found. At least that's what they are saying on their forum and they have a factory rep that participates in the thread.
I'm guessing the same would hold true with Jayco then. Here is the link to the thread.
2016 E-450 Vibration issue - Page 5 - Forest River Forums
I'm in the same boat as you Vagabond. I'm debating between the Greyhawk and the Forester. The vibration problem is common to both but the Greyhawk has the added problem of the tank less hot water heater. They had the chance to ditch it for 2016 and go back to the tried and true tank system but they seem determined to hang on to it.
I think I already would have decided on the Forester because some of the other options. Slide out awnings are standard. I really like the system used for heating the tanks and valves. I live in cold weather which means short camping seasons and something like that could extend my season up to a month.
But I can't get the local Forester dealer to get within $10 grand of the price quoted me from the Jayco dealer.