No.
The Medium Decoy would feel closer to your L Jeffsey.
And the larger an Ebike the more the weight effects (reduces) it's nimbleness
The M Decoy will feel slightly more cramped while seated due to it's steeper seat angle. But it's seatpost is only 8mm closer to the stem so either bend your elbows a miniscule bit more while seated climbing or position your saddle slightly further back. it's when stood up that mtb sizing really matters with regards to handling. either size will be comfortable to climb on when you have a motor
The Medium Decoy would feel closer to your L Jeffsey.
And the larger an Ebike the more the weight effects (reduces) it's nimbleness
The M Decoy will feel slightly more cramped while seated due to it's steeper seat angle. But it's seatpost is only 8mm closer to the stem so either bend your elbows a miniscule bit more while seated climbing or position your saddle slightly further back. it's when stood up that mtb sizing really matters with regards to handling. either size will be comfortable to climb on when you have a motor