I agree that aquasoils are easier for beginners. They can definitely build up a good amount of mulm and experience some breakdown, but I think a lot of the "mud" that people experience with aquasoils are due to never gravel vacuuming/cleaning the substrate. Felipe Oliveira and Dennis Wong both have good videos about cleaning aquasoils.
I can't comment on the longevity of aquasoil. I haven't had it turn to mud, but I also haven't had any aquasoil tanks for more than 3 years due to the frenetic pace at which I rescape my tanks.
It does seem to be great for beginners and, as @burr740
mentioned, can go longer than 3 years, but he heavily loads his water column which, as T Barr pointed out in a study, does continue to re-charge the sediment. I think that this would happen with any high CEC substrate. As I mentioned, for me, with much lower dosing, I don't think I would get beyond the initial period. Even ADA recommends finding a way to re-charge it after 2-3 years or get it out of there.
ADA also warns that, as it turns to mud, there is a high risk of cyanobacteria developing and to use that as an indication that it is time to replace it. However, I suspect that if you clean it thoroughly, you could pull out the the finer particles and leave larger particles that might encourage better circulation and extend the lifespan. Is that what you were referring to regarding the cleaning of aquasoils?
It seems like you've been in this hobby for a quite a bit longer than I have and therefore think of things at a longer time scale with regards to substrate lifespan, consistency etc. Not trying to say you're wrong, just that we have different approaches.
Yes, I'd be happy if I could leave my substrate in place for either 1) the rest of my life or 2) until/if I get tired of it.
It's been demonstrated quite convincingly that when we richly dose the water column in hard water many plants stunt severely
I've been under this impression as well but, as @burr740
just mentioned, his water is very hard (10 dGH?) and he heavily doses other nutrients to counter-balance the 40ppm Ca. We all know that his plants aren't stunted. If you have any comments on this, @burr740
, it would be interesting to hear your perspective.