It seems that it's fairly easy for active users on SciFi.SE to go over the rep cap (or at least, not very hard). We have at least a couple of people who are known to do this frequently, and probably some who do it but don't complain about it in chat à la Moaning Myrtle :)
While rep caps in general may have their value (I'm not quite clear what it is, but J&J wouldn't have invented AND kept them otherwise), they seem to be a net negative to a site:
They dampen(s8n) productivity for people who reach them and are unwilling to produce good content for the rest of the day, since it will be wasted rep points.
I don't mean to be the materialistic weasel of this group, but rep points are at least one reason why I put in the effort, among other reasons - because they are a way to keep status, which is one of the main human motivations.
We have at least 2 people who are openly on record as "I won't post anything else till 7pm today" as a rule once the cap is reached.
This seems to be a net loss to the site, especially since we aren't yet in the SO stage where we have gazillions of posters and teratons of questions and answers. IMHO, YMMV, of course I'm biased :)
They sap creative energy from people's delivery of good content into playing the stupid "lose as little rep to the cap as possible" game. There seems to be little win to the site from that game.
This is a generic concern, but it's extra hurtful on SciFi.SE because the site in general seems to be (based on recent Meta questions and answers) somewhat/heavily inflated in the amount of upvotes relative to other SE sites, and therefore it's easier to lose lots of points to rep cap here. I've lost between 200-300-350 points a day EASILY, for many days in a row.
Now, the best solution seems to be to eliminate or at least raise the rep cap (300 seems a good #, if somewhat random).
But if there's no appetite for that either from community OR from SE people, I would propose another solution:
A badge that rewards users for the amount of rep points they lose to a rep cap.
Mechanics: Award the badge for either a total lost rep points across many days (either within a period, or ever), or my preference would be for losing at least N points on average (or simply at least N points) for M consecutive days/within a period of L days.
Name: I don't have a good name, some possibilities floated in chat by me and others were, in random order:
[The first annual Montgomery Burns award for outstanding achievement in the field of excellence]
This is very distinct from "Mortarboard/Epic/Legendary" badges, which merely reward reaching rep cap. That set doesn't do anything to fix the problem of people STOPPING their creative input for the day once they reach the cap.
Any input welcome.