We have seen a number of recent prospective clients come to us after having less than satisfactory experience with the original bpm implementation team they selected. In none of these cases was the software poorly selected -- it just was not implemented professionally.
The interesting fact is that none of the consulting firms involved actually formally "quit" on the client. What they did do, though, is continually change their assigned consultants, increasingly make their talent hard to find or willing to come onsite, and gently push the client away. While some of these clients might have been among the more difficult variety, they still deserved to see their implementation completed professionally.
We know of one consulting firm that has a shortage of experienced implementation consultants, so their senior architect-level talent drifts from one "great design", but unfinished implementation to the next.
Not to say Strafford has never had a difficult client or finished 100% of our implementations, but we do work very hard to make sure every client is a happy one. We also make a point of ensuring every prospective clients meets one of the principal owners of Strafford. That way they know we are as invested in their success as they are.