It's a good investment. There used to be an outfit called "Rhiele" that
made testing machines (hardness, tensile strength, etc). They proposed what
they called "The Rhiele Axiom": One test is worth a thousand expert opinions.

Be sure and get an inductively coupled timing light (one whose sensor goes
around the spark plug wire rather than being directly connected to it).
They cost a little more but are safer and generally better. They only cost
a little more. Other than that you don't need a lot of bells and whistles
unless you can't find any shade.
--
George Downs Bartlesville, Heart of the USA!