There is nothing wrong with different modes. Even Emacs has them—and major and minor modes to boot. In any case, typing Alt-e, which switches view- or edit-mode on or off in ConnectedText has become second nature during the five years I have been using it. I don't even notice pressing these keys.
This is where some programs
There is a problem with the edit and view modes in RedNotebook: they are not clearly identifiable. In ConnectedText, I use a different font and color for the editor (light yellow) versus white. So I allways know which mode I am in. Yesterday, while fooling around with RedNotebook, I pasted a few pages into it. Or rather, I thought I had pasted a few different pages into it. But I was in View Mode, and it just looked as if I had pasted something into it. (This is particularly devious. If it did not "take" a paste at all, I might also realize that I did something wrong. But then again, I don't think that I did anything wrong. It's the program that is wrong.
Conclusion: in a modal program it should be easy to switch between two modes (using shortcut keys) and the modes should be clearly identifiable without any effort.
1. Monday, June 28, 2010: Changed in lights of WelcomeTo Isherwood's comments.