What Ayende said here that is, " Building the application using TDD, IoC, OR/M, etc would create a maintainable application, but it wouldn't be maintainable by someone who doesn't know all that. Building an application application using proven bad practices will ensure that anyone can hack at it, but that it has much higher cost to maintain and extend.

I am okay with that. Because my view is that having the developers learn a better way to build software is much less costly than continuing to produce software that is hard to maintain. In simple terms, if you need to invest a week in your developers, you will get your investment several times over when they produce better code, easier to maintain and extend and with fewer bugs."

Especially pay note to the statement: having the developers learn a better way to build software is much less costly than continuing to produce software that is hard to maintain. That's been my experience the last 18 months with our team and elsewhere. Don't punt the ball for someone else. We made that investment in our developers a year ago and it has paid for itself ten times over.