Development in Variable Width (follow up)
I am still using variable width for my development. I still have not noticed any more annoyances besides those I had already noted in my first post (space character too thin, developers that try to line stuff up too often etc.). I have corrected the space-too-thin problem by editing the font. I took the liberty of merging the monospace versions of the parentheses, angle brackets, and curly braces (I used Bitstream Vera Mono for that) into my favorite proportional font so far (Verdana - like Tahoma, but with wider spacing between letters).
I also fixed some other annoyances, such as the tiny margin on either side of single and double quotes. This made it very hard to read, and made things such as a single quote, wrapped in double quotes, a very hard thing to decipher. So I increased that margin significantly.
Then I did a couple more things. I made the parentheses (that I copied in from the monospace font) to be more concave. I like that much better. I also made their footprints wider to compensate. Then I added a dot in the middle of the zero, and even put a very thin line through the seven, just because.
I even adjusted the kerning between certain characters to make operators easier to read. I made >>, => and -> spaced closer together, but when I tested them out, I found that my development environment does not seem to take advantage of kerning. If it had, I might have also added some more operator kerning.
So for anyone who is interested, here is the font: WF-Programmer Postscript Font file