Al, I picked one up earlier the year to aid in tuning and it has been helpful. Mount it as close to direct line of sight as you can. I mounted mine under the dash...difficult to watch as I'm going down the road or 1/4 mile. I plan on moving it to the steering column.
As for tuning I've used it to lean out my cruise AFR and Jet my Secondaries for WOT. As for idle I use a vacumn gage since it only reads one bank.
Something that datalogs would make it easier...drive the car , look at the data, adjust, drive again....
It depends on how deep into the tuning you what to get..for just minor jetting issues it;s fine.