This will be a very "Short" block review. It took a second to notice a night/day difference between a modded OR4 w/turbo clocks+Hynes by itself and with the shortblock on it. The fundamental thing I hear is more presence that lends itself to a more live-you are closer to the venue/setting/etc. that the recording was done at. Most importantly, I do not hear anything being added or subtracted to the resolution-transparency-accuracy of the recording. The sound stage is larger, some that will use the term 3-D or bigger-bolder most noted in height and depth front-back. Instruments do take on a bit more impact in some cases such as the strike of a drum will be more dynamic/hard hitting/heft of tonal sound, or the strike of a cymbal will take on more impact/crash/fullness of that cymbal.
On a whole, the presence and sense of you are part of the place the artist made this recording or even close to just how the artist would most resemble sounding in real life is what makes the short block special. That it has greater impact on details, a more correct (to me) sound stage, and other more nit-picky superior elements is an added bonus.
I do not have other USB devices to give impressions about the short block and the sound with it hooked to whatever USB device can accept it (short block is not to be used on a 5V device). There is a good chance the short block will have a similar affect on other USB devices because it is capable of doing so on both the newest modded OR5 and Overdrive SE AND on the now outdated and inferior to OR5, modded OR4. If the fundamental sound was different when in use with each of these products, then you know the product is coloring the sound somehow. The fact that the fundamental sound is there regardless of the product age/sound quality/etc. means it is in fact a genuinely "neutral" product. I emphasize the word neutral because too many products garner this term, but my ears hear it entirely colored for better or worse.
I know that for me, the OR4 is good enough. But, in spite money always has to play a role in our audio purchasing habits, I would not accept the OR4 as it is, and would want either a modded OR5 WITH a short block, or if keeping the OR4, a short block for it.
This is my own .02. It may or may not be other's, but it's cheap change to demo it, and that much I can say everyone should do.