1/4" vs. 5/16" Spout under Vacuum

[corrowbasin]

I was wondering if any research has been done with the staining and nonfunctional wood vs sap output with 1/4" and 5/16" spouts under high vacuum. Does a 1/4" spout allow for tapping smaller trees while still allowing enough functional wood over the years of tapping? Or is the cost per tap too high due to the lower sap yield from the smaller tap hole and smaller tree crown to make it cost effective. Thanks

[Mark]

http://maple.dnr.cornell.edu/pubs/SpoutSize.pdf

[trevorhallam]

I would keep 5/16