admikar
Contributor
^^^^THIS.On the versions, such as DST, that lack a removable HP seat this is not a major problem. It is rare to damage the seat and, even if you do, a service tech can, 99 times out of a 100, use the Apeks HP seat polishing tool to restore the seat to normal.
Unfortunately, I don't have any pictures to show it, but what @Hickdive said is correct. Few days ago I received a DST for service. After opening it, my first step was to call the owner to come over to show him inside of his reg. It was bad. At some point, quite some time ago, it got salt water inside, on top of that, dirty salt water. I have no idea how that regulator managed to lock up. After some discussion, I agreed to do a service, with caveat of no guarantee on results. I had to polish that seat three times, but it works fine now.
I did not perform a lot of services at this point, but this was the first reg that required seat polish, so don't think that replaceable seat should be big point in your decision loop.