Bryan,
IMHO keep the channel on the canopy. You will be much
happier with the low wind noise and improved seal in
flight. Also, the airpane changes shape when in
flight. Many have used various means to mitigate the
seal issue during flight. Buckles, shims ect..
Use the channel method. It seems to solve them all.
It did for me...

Bryan,

 

Randy is correct.  In addition you will not be happy parked in a driven rainstorm when water more easily finds a path to the interior because the outer lip did not overlap the longeron.  Note that while in flight the canopy is fighting against being sucked off the airplane (low pressure inside), the highest outside forces are at the lower forward canopy corner and the upper rear.  The inside overlap is a great assist at the lower forward edge and the outside rail becomes more important towards the aft canopy as the top rear is sucked up.  With parts of the airframe and canopy ballooning out, the canopy is effectively shorter than it is whilst resting on the ground.

 

Were you at an earlier stage in building, you would be wise to review the lower forward shape of the Legacy canopy.  It is far easier to seal that area when the corner is curved rather than square.  The curve eliminates nasty rubbing at right angles to a seal element and paint.

 

Finally, at your last visit to OSH were you disturbed by the cowl/header seam not matching the canopy seam on most 300 series Lancairs?  It is only a cosmetic issue that can be hidden in the paint scheme or ignored completely.