In terms of reliability they're not a fit and forget unit (any make/model)
I think they should be viewed as you view your suspension units in that they need to be clean properly with preventative maintainance throughout the year (like air can rear shock and lower leg services on forks) and have a Full service each year to keep them running as they should.
Edit: Jambon at 6'3" I found the 4.5" of the DSP post fine for all kinds of riding, will be finding out how a the 27.2" X 3" post works fro me on my Dialled Albert I'm building at the moment, I think it depends what you're used to riding, I've ridden everything apart from really steep tech dh with saddle up for years so any drop is great

