Engine analyzers

Any recommendations (positive or negative) for engine analyzers. To be
installed in a Beech Sierra, IO360-A1B6 engine. What features are most
useful, which less so. Is fuel flow per cylinder important?
My mechanic likes the JPI. Any specific feedback on them would be helpful.

We would install the analyzer for a few reasons:
1. Desire for early problem detection in an engine that is already beyond
TBO (the engine was rebuilt, but not overhauled, as a result of a prop
strike about 800 houir ago). If things are beginning to go bad, I am hoping
that the analyzer will find them first
2. Desire to 'pamper' a 'senior-citizen' engine that, other than age and
hours, runs great, great compression, consistent oil use
3. Maybe even save some fuel dollars thru more effective leaning (only have
egt now)

Thanks in advance for your thoughts