If you're on Keith Frank's Weber/Dellorto group then there was a good discussion about meters about a year ago. I think it was back on the Yahoo days when it was "sidedraft central" (?) so the posts are probably lost by now, but if you post a question on his new group at groups.io :
sidedraft@vintagetechnologygarage.groups.io.
then I'm sure you'd get a good response. IIRC Frank uses one in his development of weber jets, etc and is very knowledgeable on this sort of kit.
I bought a Zeitronix version to use on the Europa for when I change cams, but as with all things that project has stalled - first my laziness and then the world shut down. I did weld a plug on the Elan exhaust to try it and yep, they do work. I don't have enough experience to say if it's good/bad/average, I've only tried it once.
If you're using it in a workshop then a simple gauge works fine but it's probably more useful for the DIY guy without a rolling road to be able to drive the car and see what happens.
That's more complex because you need the revs/throttle/mixture data which becomes expensive but if you are going to use it regularly to tune an unknown engine then it's probably worth getting it on your laptop. You can mount the gauge and keep glancing at it but I wasn't confident with trying to drive and watch the gauge - it's a personal thing.
I had a bodgy solution which I copied from a poster on Frank's group where I made a case for the meter with a digital rev counter alongside. Put it in the footwell, point a video camera (or your phone) at it and then talk through the drive. Best to do it on quiet roads or other motorists will think you're talking to yourself !
Brian
