I'll agree with one important point that you make after restating simply:
There's no such thing as a 'calibrated' meter.
By that I mean, taking a an A9L in combination with a 'calibrated' meter and any size injector other than 19s is an exercise in frustration.
Have I built a meter before? Attempted yes. Not with a piece of PVC though. I was matching different electronics into other meter housings. The problem that I ran into was scaling. The meter output often wasn't repeatable from run to run. It probably had more to do with the shape of the housing vs. the shape of the various element housings but the point is that a QUALITY meter is designed, housing to element, to be accurate and repeatable.
What's more... I can safely say that I've pretty much run the gambit of meters on various applications. Some are MUCH more precise than others. There's a reason why sample tube meters have developed their reputation for being inconsistent. Some of the better meters... PMAS if def one of them. The Lightning meter and SCT meters are also pretty damned good. Why? They're consistent.
But I digress... Make yourself a homemade meter. Tune it with whatever your tuner of choice is using a dyno, wideband, what-have-you. You will likely discover the frustration that comes from dissimilar results from your wide-band/RPM data graphs.
You can have the best tuner in the world but if meter output is erratic, and/or unstable, you're pissing int he wind.
All that said... I can't honestly say that I've not seen success stories with a C&L. I've actually been part of making a few of them run pretty damned good. One instance was just a matter of reclocking the meter to change how air entered. A couple of other needed to have actual enclosures built around them to smooth out airflow. Others required changing the shape of the air tract both, before and after the meter housing. My point? They're consistently inconsistent. I attribute a lot of that to the 'one size fits all' approach to the interchangeable and user installed sample tubes. The other meters I've mentioned above, are bench flowed as assemblies. It's not often you'll find those types of meter so severely affected by the air inlet tract (although I've seen what I refer to as the 'good' meters need adjustment on that rare occasion).
It's kind of like buying the difference between a Walmart shotgun and something you might buy from Sharps.
