@join
Thank you so much for the feedback. I am new to this kind of analysis / testing, but I really want to understand how this all works to get the best control over my sound ...
Settings are provided below. Key settings I guess are:
** MIDI Mapping
Breath rate:		Low (125 Hz)	-- Based on the XpressO and Ingo's advice
Velocity:		Dynamic
	Capture delay:	20ms
** Keys
Reaction time:		20ms
Breath rate is Low / 125Hz because of the XpressO, which was choking (for a while, at least) on Medium and above.
Velocity = Dynamic because many of the VSTs I use depend on that. My VL70-m is fantastic, but I currently have a (very) hybrid rig (still in the expansion / exploration phase with my rig).
Key Feature would be a way to re-configure the Sylphyo via MIDI program changes. I could then switch settings when switching sound rendering modules or VSTs. Without that, I am really stuck with the "least common denominator" across all my sound rendering tools.
I am not sure what your term "key debounce time" is ... is it Keys / Reaction time?
I will use 15 - Cheap Tunes in the future for testing ... (that sounds the most immediate to me of the choices you suggested).
Thanks again!!
@peter-ostry
I never considered that the sound triggering mechanism might be other than MIDI. But, of course, analog synths use CV and that's a whole 'nother world ... would love to understand how this actually works on the Sylphyo!
All the settings I used for latency tests:
Clint's Configuration Settings for the Aodyo Sylphyo
Firmware version: 1.4.8
As of 11/27/2021
* Sound
	Volume:	100%
	Reverb:	 70%
* MIDI Mapping
	Breath: CC 2
	...and	---
	...and	---
	Breath rate:	Low (125 Hz)	-- Based on the XpressO and Ingo's advice
	...per CC:	On
	Delay notes if needed:	On
	Velocity:		Dynamic
		Capture delay:	20ms
		Max. velocity:	127
	Slider ctrl.		CC 1
	Top slider ctrl.	CC 12
	Btm. slider ctrl.	CC 13
	Elevation ctrl.		CC 75
	Roll ctrl.		CC 76
	Compass ctrl.		CC 77
	Key-bend ctrl.		CC 78
	Program change >
		Send Bank	Off
		Bank (MSB)	---
		Bank (LSB)	---
	Note-off delay		10ms
	
* Breath
	Minimum:	 20
	Range:		600
	Curve:		Log
	Filtering:	On
* Keys
	Fingering:	NativeFlute+
		Octaves:	   5(+2) octaves
		Invert ocatves:	   Disabled
		Left pinky: -1st:  Disabled
		Right pinky: +1st: Disabled
		Replay same note:  Disabled
	Reaction time:  20ms
	R.time octaves: 20ms	(If [Reaction time] is 0ms, then this must be 0ms)
	More sensitive: Enabled
	Key-bend (BETA):  PB+
	Key noise (BETA): Disabled
* Slider
	Function:  Ctrl (latch)
	Top edge:  Bend -
	Btm. edge: Ctrl.
		Edge size: 9mm
	
* Movement
	Shake to move:		On
	Shake vibrato:		On
		Range:		20%
		Sensitivity:	43%
		Threshold:	 9%
	Elevation control:	On
		Bidirectional:	Off
		Absolute:	Off
		Range:		+-35 degrees
	Roll control:		On
		Bidirectional:	On
		Absolute:	Off
		Range:		+-20 degrees
	Compass ctrl. (BETA):	On
		Absolute:	Off
		Bidirectional:	Off
		Range:		+-20 degrees
	Always on:		Off
----
* Base Key: A3
* Output: MIDI ch. 1
----
* Invert Display: Off
* Receiver device: Connected CH 23
* LED: Off