I haven't found these fractional sites to be very useful for development work. The rates are low and the few dev jobs already have 100s of applications.
Probably mediocre. Even absent being a source of full-time income accounting for the fact that there's going to be a lot of unpaid/dead time, I personally won't take a job for less than $1K for a day+-ish unless it's really interesting or I'm doing a favor for someone I know.
(One of the issues with short-term fractional work as an income source is that you can end up only being paid for a fairly small percentage of your total time. If the rate is good, that may be fine as a part-time job. But in my prior industry analyst stint, we actually had quite good day rates but we spent most of our time keeping up with industry happenings and writing free stuff.)
