I hadn't considered Paracesis' bonus damage against sentients. We tried using two Mesas and it didn't work out. Enemies scaled faster than our damage and eventually we wiped on a toxin damage bonus.
That's an interesting question I hadn't considered. I'd say that I don't think the bonuses are necessary for other endless missions, but that's because my objective in the other missions is something I am incrementally achieving. For example, if I'm going for relics I'll do four rounds, then if I know I can easily do more I will, otherwise I restart. If I'm going for affinity, I stop whenever I have enough or can't kill enemies fast enough. Basically, I never have a reason to go for an hour, and I usually think that anyone pushing themselves to go that long is doing it just to see how long they can go, at which point there is no real failure; every passing second is the reward. With these challenges, on the other hand, there is a material reward, but it requires non stop attention for a lot longer than I would normally run a mission, and into enemy difficulties that I usually avoid so I can better enjoy the game. The normal rewards for doing disruption don't count to me because I could just get those running the mission normally.
I think the challenge to do more, to push myself and work on my builds, is great. But it feels like... I don't know. Like there's no reward for challenging myself if I fail, and therefore unless I'm certain it's a waste to even try, but there's no other content to practice on to get better, so I normally don't bother.