My 2c worth
Those are excellent explanations of the working of the system. I replaced the accumulators on both my 300D wagon and my 560SEL and its a simple job - no more difficult than changing shock absorbers, and the hydraulic pump is self-bleeding to make matters easier.
Both cars had close to 100,000 miles at the time and while they sat level, had an extreme 'pogo stick' quality to the ride over bumps.
Just one caution when you replace these - use a flare nut wrench not a regular open wrench to undo the hydraulic connections. They are brass (?) and easily damaged - a flare nut wrench (a few dollars at your car parts place) will do the job right.
Each accumulatror cost $100 or so, if I recall correctly.