Premature end

[washed up contractor]

What are the thoughts on leaving a gig prematurely?

If you worked in a relatively niche area and had been at a client for a reasonable period of time, but in addition to the realisation that they are rather dysfunctional in several key areas with no real likelihood or prospect of improvement, you have a better paid and more interesting opportunity arise? Consider that opportunities in said niche area are obviously less frequent, thus they demand serious consideration, but this is set against an upcoming project with existing client that could potentially be impacted by leaving, though not by as much as they might think.
Asking for a friend.

Asking for a friend, ho ho. Given the state of the testing market,(presuming you are in testing?) Id be very wary of leaving a role without anything lined up to go to. You may be in a geographic area where the testing market is very strong but if not, you could either be benched for some time or face having to stay a considerable distance from home.