I only have the SGH-6, which is a straight shotgun version.
The SSH-6 is really quite a bit different as its a bit of a hyped up mid-side mic with effectively a mono shotgun input being merged with the stereo inputs from the side mics. Amazon UK has a review of this by a competent sounding purchaser. He has mixed feelings. Apparently the H-5 and presumeably the H-6 need to be running v 2.0 firmware, since it came out in 2015, most folks probably are.
I was going to get the cable that lets you detach the microphone from the recorder and mount it on a shockmount grip, but realised that the volume control goes with it.
I actually quite like the idea of the SSH-6 but for me it would be for other uses than wildlife.
Unfortunately the need for using the SGH-6 mounted directly onto my H5 hasn't really materialised since I got it, partly due to a massive cut back in my normal activities since the CV19 outbreak with other things filling my time, so I am not qualified to comment on it. My first impression was that you might find it frustrating if you looked at it as an ME66 substitute, but thats hardly definitive!
Anyway its less frustrating than the version of Zooms website I get in the UK (it may be the same worldwide) that is doubtlessly designed by a marketing department that has no regard for anyone trying to find out any facts and is probably helping Tascam sales greatly! Its very pretty or something!!!!
Buyer reviwers elsewhere stste that the SSH-6 is that it records quite a wide angle compared to longer shotguns, but its users have uses where this does not matter. For the more popular SGH-6 folks rate it as a close to medium range shotgun useful for say journalism or video with one reviewer saying that its not really for birds. Whether he has actually tried using it for birds seems doubtful.
Sorry I can't be much help on this one, but thanks for reminding me to get it out sometime.