Even though you know "their existence is an old and well known fact" you felt the need to post it, but when others also mention it you feel the need to be sarcastic ... how logicalRelax, we are not stealing your thunder, I did read and understand that you were already aware of their existence, I was merely stating my experience of having used Metaz flash and also having tried the Sigma USB dock ... so the credit for mentioning them first goes only to youTheir existence is an old and well known fact, especially on a rumor site where new products are discussed in depth many weeks/months before their official announcement.
My posting was deliberately sarcastic and aimed at people who perpetuate the "then Canon changes the protocol and my expensive third party accessory will be worthless" meme. These times are over, they have been over for over a decade AFAIK, and we should put that meme to rest already.
Anyway, FYI my first DSLR was bought about 8 years ago and it was a Nikon D70 (and later on my first Canon was a 400D), at that time, other than the 18-55 kits lens that came with the camera, I had bought only Sigma & Tamron lenses, because I was not willing to spend more for OEM lenses ... and all of the third party lenses I had bought did a great job, until I upgraded to a new camera or updated the firmware. Since the past 8 years I have owned the following third party lenses:
Sigma 10-20 (Canon mount)
Sigma 10-20 f/3.5 (Nikon mount)
Sigma 17-50 f2.8 (non OS - Canon mount)
Sigma 17-50 f/2.8 OS (Nikon mount)
Sigma 18-200 OS (Canon mount)
Sigma 18-250 OS (Nikon mount)
Sigma 150mm f/2.8 Macro (Non-OS - Nikon mount)
Sigma 150mm f/2.8 Macro OS (Canon mount)
Sigma 50-500 (non OS - Canon mount)
Sigma 150-500 OS (Canon mount)
Sigma 150-500 OS (Nikon mount)
Tamron 17-50 f2.8 OS (Nikon mount)
Tamron 17-50 f2.8 OS (Canon mount)
Tamron 24-70 f/2.8 VC (Canon mount)
Tamron 90mm f/2.8 Macro (Canon mount)
Tokina 11-16 (Canon mount)
Rokinon 24mm f3.5 T/S (Canon mount)
(I'm pretty sure I had a few more third party lenses, but cannot recollect all of them)
Every single one of those lenses developed some issueor another with AF or OS/VC after upgrading to a new camera or firmware, they would suddenly start hunting for auto focusing on a subject or the image stabilization would take longer to be activated and/or drain the battery with the OS/VC on even when they were not being used ... were they useless? absolutely not, coz I could still get great images with every one of them (except the Rokinon T/S, which was just a sh!tty lens from the beginning) but the issues they developed were annoying. I am sure a visit to the the third party manufacturers service center will fix those issues, but (as mentioned earlier) where I live there is no service center for third party lens manufacturers ... so I basically sell my third party gear whenever I upgrade to a new camera or new firmware ... luckily I have several friends and colleagues who are always willing to buy my camera gear ... the last 2 third party lenses I sold were the Sigma 150-500 OS & Tamron 24-70 VC about a few weeks ago. But I will still buy the Sigma 18-35 f/1.8 lens for my Canon 70D (knowing full well that many people are reporting AF hunting issues) but I don't think third party lenses are "worthless".