I really must take issue with that claim, in rather strong terms. I’ve posted plenty of detail in the past, including comparative screenshots.
If you would like more info now, for example about any of my test clips (a couple of which, incidentally, are exactly the same clips as some of @Scottosan 's!) and about what they illustrate, then by all means let’s have that conversation.
Of the clips I’ve posted, probably the two most important ones are the bit from Sherlock and the bit from Time Flight (a classic Doctor Who story). Here’s the download link again:
Let’s start with the Sherlock clip, which is 1080i/50 h.264, and is designed to show what happens when the material is frame-interlaced but the deinterlacer misidentifies it as field-interlaced.
Ignore the first couple of seconds; after that the clip mainly consists of Sherlock himself (in the black jacket) talking to Mycroft (in the light grey suit). If you can, try watching the clip first on a Pi 3, with deinterlacing set to Off: this is what it should look like. Note, in particular, the fine check pattern on Mycroft’s grey suit - you get a nice steady close-up of it when the two men stand next to each other from about 00:30 to about 00:47. Compare that to what you see on the Vero 4K: instead of being able to see the check pattern on the grey suit clearly you get a shimmering moiré-like pattern.
If you don’t have a Pi 3 to hand then try using Kodi’s screenshot facility during playback: for some reason the screenshot comes out looking the way it should, and very different from what you see on screen.
The Time Flight clip is 576i/50 MPEG2 and is designed to show the problems caused by the lack of diagonal filtering when playing something that is field-interlaced.
I suggest you start by playing it (on a Vero device) with software decoding and deinterlacing set to Deinterlace. This is roughly what it should look like (although there is some odd stuttering sometimes when playing in software). Now try playing it with hardware decoding. Watch, in particular, the control console between about 0:11 and 0:15, and then again between 0:34 and 0:38 - notice all the jagged edges along the sides of the white or reflective areas. Also worth looking out for is the horizontal line of darkened pixels at the top left of the screen: in software they appear simply as dark, but in hardware there’s a very obvious flicker.
(Incidentally, there’s an unrelated bug that causes horrifically jerky playback on 576i/50 stuff with hardware decoding if the whitelist is active but you don’t whitelist anything below 1080p - I already raised that here - I mention that just because I happened to bump into it again today!).