One thing I worry about is that this funding model only works for somewhat popular developers. You need to be well known to get people to donate to you monthly.

If you're a person that prefers to just do some work and not talk about it much, this kind of sponsorship model wont work.

To me, something like bountysource seems like an awesome model: people could all chip in to support a feature request or an issue, and anyone who is familiar enough with the subject matter can do the work.

(Unfortunately the reward mostly seemed way too little for the effort required -- it would be a nice bonus if you would do the work anyway, but I don't think you could make a living by implementing issues from bountysource)