Stepped Baffles

Reason I ask is that there is a TG design I like but would prefer a flat baffle rather than the designed stepped baffle. One other thing is that my HF hearing is poor as I am getting on a bit so would I notice anyway
Most of it would be bragging rights in vertical measurement.

Otherwise there is plenty of systems where vertical is nothing special.
But drivers speak for themselves.

Sound quality real world is what it is
and good detail is found with many tweeters.
So anything noticed, not really.

Its still the basics with any tweeter.
Sound quality is the driver itself.
And at higher SPL
less distortion if not crossed to low.
And by far 3rd order is so simple and easy to achieve.
Which helps at higher volumes/ SPL
Hi, how did you do the tuning!? sliding tweeter live from arms length distance? or did you have a friend/robot to move it while you listen bit further away? Or AB testing with different speakers? How is your xo?

I'm mostly interested audibility of it and I believe you there is a difference, at least close listening. I should do more listening tests on this.
I do all of the above (use my feet instead of friend) and the result/effect is consistent at any distance and (surprisingly) different frequency bands (doublebass/cello/violin for example -- suggesting what is relied on is "air"). Provided that adequate, common sense testing conditions and procedures are satisfied/followed as outlined below.

Ideally one should first align drivers' acoustic centers (via manufacturer info or eyeball-then-tweak). Then design XO (by tweaking values if necessary) such that at the XO frequency, phase is also aligned. This latter is verifiable by ear using a test tone, the combined loudness should be maximum over varying offsets (periodicity being XO wavelength). Then, when music is played (just one channel), a floating image or sense of air is present. (If the offset is now changed the effect vanishes.) Now play both channels, any distance, each tweeter axially aimed at one ear, but must be from L/R-front (not directly front nor directly from the side), where hearing is most sensitive, and a holographic soundstage should materialize. (This speaker placement and listening position combination can be assured by playing a test tone at the hearing upper limit frequency.) If the acoustic centers aren't aligned but phase is aligned at (ONLY) the XO frequency, the imaging will be far less holographic -- IN MY EXPERIENCE.

Whether or not one normally listened to music from the sweet spot, the above yields what is possible.