Everything seems easy until you actually get your project management organization involved, and your IT staff, your QA, your business analysts, your compliance department, start allocating cost for your staff etc....
Well that's because you're locked-in :). If you're already locked in, you're screwed and have to work your way out or live with it and the consequences that come either now or later.
If I get to make the call and I care one bit about the business beyond next quarter, I would always have a clear way out to heavily reduce risks to a situation that we have seen play out many times before with the Oracles and IBMs of the world.
