Thought I would share my experience with you all ....
Got the letter and got the V6 box. What a disappointment! Picture quality compared to Tivo terrible: read numerous posts over two days on this forum (and elsewhere on the internet) and tried every conceivable video-output configuration in an attempt to match the Tivo screen quality; swopped cables and HDMI ports, checked signal/SNR strength and ratio and have attempted to get the TV to improve things - I have failed. Yes, the Tivo is more "grainy" but that can be corrected by the TV but "graininess" is the lesser of two evils compared with blurriness or lack of resolution - ask any photographer; no amount of TV sharpening (which several people suggested) is going to improve the picture if the information is not there in the first place. In my case the V6 output was worst that my terrestrial TV input.
Anyway, have wired my Tivo back in place and I will give Virgin perhaps a year or two to improve things before I'm tempted to try again. As for 4k UHD? - I'll stick to my TV's internet to watch such stuff (it's a Samsung QLED9 in case anyone thinks it's a problem with the TV itself, which there isn't) or just pop something into the 4K blu-ray player.
I've now got to try and persuade Virgin to take the V6 back and reduce my premium back to what it was before ...
Before signing off, and as mentioned above, I've spent days trawling this forum and there is a huge amount of information on it; nothing worked for me in this instance but without doubt it was a useful experience nonetheless. Thank you.
There are also lots of people on Virgin having no problems with the V6 whatsoever. There are now around 2 million V6 boxes in use. I have 2 & the picture on them is better than the Freeview HD from the TVs own internal tuners.
This could quite possibly be a faulty box, so I would try getting a tech out to fix it. I'm not sure what the future of the TiVO will be. The V6 is the gateway to using LGs Horizon 4 firmware which is now in use in their other European franchises.
Cable customer since 1993. Services: FH TV, Sky Sports/Cinema (2xV6), Talk Anytime Phone, 350M BB, Virgin PAYG Mobile
Yes I will request an engineer visit - you never know, maybe I did receive a faulty box.
In respect of the video settings suggested and purely for interest, that particular configuration was the worst for me: selecting 2160 was great for the one UHD channel available but it's effect on all the other channels was terrible - even the HD ones; my "best combination" (but by no means acceptable) was 1080i and 1080p pass-through.
...just to play devil's advocate here, wouldn't having 2160p 24/25/30fps (pass-through) AND 2160p ticked, cancel each other out?
Having 2160p 24/25/30fps (pass-through) ticked, passes all HD content straight through to the TV to upscale but also having 2160p ticked, also passes HD content through to the V6 to upscale - surely you would need only one of these ticked and not both (if HD comes through and you have both ticked, then the V6 AND the TV are both upscaling the content)??!