I use the sewer solution ( http://www.sewersolution.com/
) for hookup camping, and the slinky for dumping after dry camping. I take one or the other, rarely both. The sewer solution stores easily in teh back bumper compartment, I keep it in a trash bag, away from the power cable etc.
I like the sewer solution because you don't need hose suports, and it's very easy to store. I bought an extension hose for it, and it even works up hill, when dumping the black tank.
I do believe that every once in a while, a good flush with the large diameter hose is important. The tank flushes faster, with less chance for deposits.
I had my sewer solition over a year now,and it seems to be a good quality product, just like they promised.