I would agree somewhat Brian.
I think if it's possible to repair a surface without splines then definetly that is the path to go.
Backplates are also options, I actually have a Martin 12 string that came in this morning that I'm doing a backplate repair on.
I also think any spline fitted should not use an end grain join, there is no strength imparted at the ends and this is where I totally agree with you, they can weaken a join to the point of guaranteed failure
P.S, i perused your repairs, the finish work on this one is impressive -
http://howardguitars.blogspot.com.au...ck-repair.html
Steve