Those two types of missions seem like decent ways of obtaining experience, even for a Survival character. I'm looking forward to being able to use a Vertibird around the Commonwealth for faster travel, but after the mission 'Reunions' the Prydwen arrives in the Commonwealth and I am taken to it. I fear when I progress far enough into the game to obtain access to a Vertibird, I will end the two aforementioned radiant quests.
The only thing that will screw that up is if you make enemies with the Brotherhood by allying too tightly with the other factions. Specifically, if you keep doing the main quest lines for the other factions, you will eventually get a message before accepting a quest, something along the lines of: "warning: this will make you a permanent enemy of the Brotherhood".
On the other hand, all the other factions have similar repetitive, semi-random quests too.
As long as Haylen and Rhys are alive, they will continuously give you this quest, as Preston would with his settlement quest. So go on, take that Vertibird and have fun messing around
Source : Personal experience and https://www.reddit.com/r/Fallout/comments/3siy1r/is_there_an_end_to_cleansing_the_commonwealth_in/