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These aren't my measurement, just sharing some data that someone else has shared with me.
ND25FW is a low cost dome tweeter with a nice small waveguide. As of today, it's cost is USD$22 making it one of the cheapest waveguide tweeter options available.
It was installed in a bookshelf cabinet along with a SB PFCR series woofer:
Measured frequency response is very promising.
You may be concerned that the high Fs of ~1400Hz is a problem, but it is a fairly small peak as this tweeter uses ferrofluid:
For a basic crossover example, a simple 2nd order filter was built.
And here's the transfer function of that filter. As you can see, the impedance creates a bit of a bump in the knee of the response, but not enough to be too concerned about, especially at $22.