Do ClassDAudio Amps Have Proper Decay Of Notes?

["Just so we are clear here, class D is not digital. Its an analog process."]

Absolutly.

I believe there was one self described "Digital" amplifier but I can't recall the brand. I didn't refer to any class D amplifier as digital.  Some reviewers have used examples of stepped digital waveforms to describe or imply what the typical, or some, switching amplifiers using pules width modulators are outputting. 

My QSC PLX 2400 Bass rig amplifier has a switching power supply that makes a hell of a mechanical noise but it can't be heard in the output. I may be getting too old but unless we're talking about substantial difference in the amplifiers basic presentation I have yet to hear any class D amplifier produce switching noise.

I just aquired an sds-470c upg
tested for 10h on different gear
DON?T BUY IS TOTAL CRAP!
it sound clean aire and tight bass.
BUT I NEVER HEARD AN AMP THAT SO CAPABLE TO DESTROY THE MUSICAL MESSAGE. This amp doesn't a penny....
+It seems that support is not honored!

No,.  No they dont

Just to throw out a thought -- shouldn't whatever "decay" a musical sound possesses be solely on the recording? And isn't it the job of the equipment in the playback chain to simply reflect, as accurately as possible, what's on the recording? 

Decay is the remainder of a note as it fades away. For an amp to mess that up, it means the amp is either non-linear in some fashion, or has distortion that masks lower level sounds, or noise (another form of distortion) that is masking the signal as it decreases in volume. 

You'd think those deficiencies would show up in more areas of playback than just decay quality.

I've got a Bel Canto C5i and I find it wonderfully neutral. 

I have c5i also.   Fabulous device!