In the last two weeks Google added a sites option to content search. AdWords is evolving. An API development system that doesn't offer substantially identical services is less useful. If Google created a different server system to support development, it'd need running off the same code. Hence a need to keep in synch with the real system.

I'm slightly less concerned about data synchronsation, but there are things that you only learn when you do something for real. For example, we've found some issues in the area of estimation and budgets that we would not have found if we weren't spending money on real adverts.

I'll gleefully maintain that the development environment is *more* useful if it is both up to date with the system available to end users, and if it can be used to manage real world problems. That doesn't prohibit test accounts - not tied to real spending, generating no visible adverts and with faked historical data to test reporting.

I'd rather see test accounts with unlimited ops budgets than an isolated, downrev, data-free development system. YMMV :)