One view of "archival" is that it should be reversible.
Using that definition, neither the spray adhesive nor dry
mount tissue are archival. Either way, the print can only
last as long as the mount does, and if the mount is
damaged, it cannot be replaced without severe
risk to the print.
How about 3M Spray Mount Artist's Adhesive? Mounted
works can be peeled off. Must be some using it. May be
as good as wheat or rice starch. Dan
The reason one of the best practices for archival is completely reversible is since the frame components get contaminated over time you can eventually swap them all out with fresh components.
If you are going to forgo reversibility, you have two things to consider. One is will the process damage the print. Dry mounting can damage some types of artwork and some adhesives are harmful. Assuming the process is not harmful the next question is how permanent is the process. Permanence of the process is critical for longevity if you cannot reverse it and redo it later. Permanence is where dry mounting does very well and it is where spray adhesives tend to do poorly.