the smoke:d4v3pum4:
Usually the errors (if any) that are encountered with long length hdmi cables are sparklies or simply no picture at all. I can highly recommend the
octava cables or bettercables (I use one for my projector run) at tmfsolutions,
hdcable or
bluejeanscables. These guys have a good reputation and guarantee the cables and should be considerably cheaper than QED.
Mark Grant also comes highly recommended and actually tests each individual cable. I would make sure you test the cable before chasing it in a wall in a permanent install.
There is a handy guide on HDMI cables
HERE which should hopefully answer any queries you have. Do a search as well as the topic comes up quite a lot.
All of these brands etc, logic of "all HDMI cables are the same" etc is very heavily pushed by "AnotherForum".
Bear in mind these brands advertise heavily there and therefore the so called "user reviews" are as susceptible to bias as "What HiFi?" is accused of by them.
IMHO, check out "What HiFi?" first and get yourself an expert review's opinion.
All I can say is that I haven't found any difference between freebie Sky HDMI cable, £4.99 ThatCable, £40 QED Performance HDMI & Chord Supershield HDMI cable that I got for What Hi-Fi subscription.
My opinion is to check a £5 cable first & compare it with a more expensive HDMI cable bought from a shop with returns policy & check for yourself if you note a difference & if the extra cost is worth the performance improvement, if any.
I'm not sure about the "other forum", but there are articles & scientific tests online as well, which suggest the same. You can search my previous posts for the tests, articles etc.
Some people note a difference & some don't. Just buy a cable you're most happy & comfortable with (many won't be comfortable buying a £5 cable for their £10000 system).
PS: On that note, even I'm not entirely comfortable buying a £0.01 cable available on Amazon & Ebay, £5 is my minimum limit