While we are on the topic of listing problems with consultants/outsourcing - another potential problem is the A team/ B team switch. During initial engagement you are often talking to somebody who appears to actually know their stuff - you hire them and find that this knowledgable person has moved on to the next big sales, and you've got the B or C team.
I have heard this before, but my experience when working as Consultant, is that Customers will do a lot of diligence before accepting a substitute. Maybe these are Contractors and not Consultants? ;-)
If it's a small firm or a 1 person contract then sure.