Though, since I have a router plane, is it more worthwhile to continue using that to clean out dados and such (especially since I already have a dado plane), or will the plow plane simply be more versatile?
A plow plane is for cutting grooves/slots with the grain. My plow planes get regular use. A dado plane cuts across the grain which is why dado planes have knickers. Be careful to not get them in a twist.
Most of the time my dados are stopped on the exposed end. Often they are stopped on both ends. This makes the router plane useful over a dado plane. Most of the time my dados are cut with a chisel or two.
A side rabbet is very useful if you want to trim dados, rabbets and plowed grooves. It is a handy tool to have. It is not a priority tool.
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)