I can relate with your roadblock about the surrealty of the world that is presented. It's one of the weaknesses of the style. How the hell does X work if yadda yadda... But the point is not so much the believability of the World, as the author would have it; it's all a parable-scape to explore the topic at hand. The topic at hand seems to be the incessant rage for the world that does not understand Ellison's own eccentricities.
If there's one thing I've learned from 20-or-so scificlubs, it's that there's a range of certain aspects that determine how we respond to literature. One such aspect is the willful suspension of disbelief. A generous willful suspension of disbelief will not poke at faults in Repent, but a strict one will reject it completely.
I think there's a limited number of dimensions on which can describe our tastes in literature and predict it effectively (willful suspension of disbelief being one. Prosaity, for example, could be another). I'd like to develop an idea of these dimensions as the club progresses.