You came on here to ask for advice, have been given advice, but choose to argue with it, presumably because of your own thoughts and prejudices. If you just wanted to confirm your own assumptions, this is the wrong forum. That attitude does not sit well with those giving the benefit of their experience and wisdom, many of which have good memories. This can affect whether further advice is forthcoming.
The FIRE engine was a simple design, and has proven very reliable, and as a result is the most popular unit on here, and well loved. If serviced properly, with correct oil change intervals, the valve clearances rarely need attention. Searching YouTube, or anywhere else, will only find those who've needed to, as a video of not needing to adjust them is hardly worht posting.
The early Cinq 899 engines had troublesome hydraulic tappets, many needing replacement under warranty, and many more needing replacement later in life. The FIRE engines are significantly more reliable.