Yes but what about when you use your other HDMI devices that know how to select 16:9 all by themseleves when required?

Automan.

There is a major error in my previous post - the TV aspect ratio is set to 4:3.

I do not have any other HDMI devices, but presumably the 16:9 flag will be recognised in the same way it previously was with the Humax, so long as the TV default is set to 4:3.

Yes, I think most people find V.Format = 1080i works OK. The problem with that is that it uses the inferior* Humax upscaler for SD. The real problem is getting the correct aspect ratio when using V.Format = Original which instead will use the TV's better* upscaler.
(* Whether the TV's upscaler is better than the HDR's is only an opinion and will depend on the TV used.)

I agree the Humax picture is not as good as the TV's, but in order to use the original format it appears that the TV needs to see a 16:9 flag - which is the bit they broke. We have to choose between quality or convenience now.

My telly is a Panasonic TH-42PZ85B, I honestly can't tell the difference between the upscaler in the TV and from the Humax. When having the HDR on original the channel changing is more 'clunky' and the EPG is lower resolution.

I've been using these settings recently:

TV
Aspect Ratio 16:9 or Auto
Overscan off

HDR
Screen Ratio 16:9
Display Format - Auto

V.Format 1080i

The aspect ratio on the TV set to Auto or 16:9 makes little difference (just some overscan on auto)

If I have the display format on the HDR set to 4:3 then i get the letter boxing on certain channels.
Whatever set up I use there are still intermittent problems with the screen jumping to a different format.