Thank you, Stretch. I value your advice based on your experience.

I am aspiring to turn my hobby into a professional level service.

Right now I have a Fluke 83V and Rigol DS1102E as DVOM and oscilloscope respectively. They are robust enough for repeatable data I can depend on.

My interest in monitoring CO is for personal educational purposes. Being an autodidact I like to have all the data in front of me to decide what has the greatest value to make accurate and effective decisions. I doubt the CO monitoring tool will have value to be in my daily routine.

I like the idea of '80's second hand equipment that can still hold a calibration.

I agree the newer diagnostic tools I see others use in general are over-priced gadgetry. If I wanted to play video games I'd buy a console. I'm too old for childs' play.

Coming from the background of non-destructive test equipment manufacturing combined with a brief but informative position in a thermodynamics laboratory I have had an education in what is substantial and what is superfluous.

Admittedly my experience with a CO meter will most likely be brief and it will end up sitting in the cabinet next to an almost museum level collection of archaic obsolete equipment. But then I appreciate a certain responsible level of clutter...

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I do not 'believe'. I have no use or time for this distraction. A'priori is antiquated furniture that clutters the mind and deteriorates society. Instead I investigate, research, scrutinize then choose from data what best serves as a suitable answer until a new idea or material is presented. Then I start the process again.