Here's just one paper on PubMed. I'm tired and want to go to bed. Unfortunately, there's not a lot of research on the actual aquariums out there, but there are a few things that we can say.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2644126/?tool=pmcentrez&report=abstract
Ocean acidification impairs olfactory discrimination and homing ability of a marine fish
1) Lower pH is bad for marine fish
2) Urea is acidic
3) build up of urea causes lower pH
4) addition of buffers will correct lower pH - UP TO A POINT
5) once you've added a certain amount of buffer, the negative components of the buffer mixture will lower pH despite the addition of additional buffer.
This is basic chemistry. There is nothing that can increase the pH of marine water once certain chemical pathways are saturated.
Admittedly, this takes a much longer time than most freshwater tanks... which in many cases contain fish that are actually more delicate than marine fish (I've had a few).
A partial water change will reset (at least partially) the chemical pathway for the maintenance of pH (indeed, it does the same for other chemical pathways as well, ammonia, nitrites, nitrites, phosphorus, etc). A regular water change will prevent the chemical pathways from ever 'clogging up' and needing emergency maintenance.
Again, it needs to be said that freshwater fish can often survive quite happily in water that is not ideal. Again, it's survival. Roughly akin to the guy who hasn't cleaned his apartment in 2 years. You can live in it, but who wants to.
Now, as far as anecdotal evidence goes... I had two tanks: a 55g freshwater tank planted with cories, black skirt tetras and neons, and a 46g reef tank with much natural life (in fact the entire tanks was basicaly 75 pounds of Gulf of Mexico reef removed and dropped into my tank (arguably as close to natural as you can get)).
Hurricane Ike comes in and we lose power for 6 weeks. The SW tank was the third most disgusting thing I've ever dealt with in my entire life. The freshwater tank had some algae growth... didn't even lose a fish. As far as I know, every fish I had is still alive.