L lenses are pro lenses by definition.I don’t get it. The EF 24-70/2.8 and RF 28-70/2 have extending barrels. Are they not ‘pro-level’ lenses?
The 100-400mm MII is as good a lens as is made (Even primes) in durability, and optical quality. It extends and is NOT a collector of dust, well sealed. I have had mine for several years now and no dust with heavy use in desert environments etc.
There are the you tube arm chair commentators and real users.
I really get tired of those who have never used a lens, especially in tough environments, making any comment except for click bait you tube videos.
PS I also have it out in wet weather and no problems either.