It would be remiss of me not to mention the strides the developer, Oliver Furnib, has made in the weeks since I posted my thoughts on Mr. Reader. He's issued two updates that go a long way towards fixing what was the most glaring issue (i.e., instability; the app hasn't crashed once for me since the first of those updates), and it's clear he's taken a number of my recommendations/complaints to heart.
Surely I'll list a few more niggles at some point, but for now I'll just stand back and let Oliver continue to position Mr. Reader as the go-to RSS app on my iPad.