This is a good question, because except for real large jobs, I can't
imagine not being able to use a router for most anything a shaper can
do. Your statement about a lock miter. For 3/4 stock couldn't you use
the lock miters just a well that are made for routers? It would seem
that height, depth, speed and the ability to take the punishment for
hours, days and years are the forte of a shaper. For me and most other
"weekend warriers" a router should do the job--right?