Balancing innovation with stability starts by setting clear expectations with the client upfront. We prioritize features based on impact and gradually roll them out to minimize risk while keeping an open line for feedback. This way, we ensure the system stays stable without stifling innovation.

One of the common mistakes with Enterprises implementing new systems is over expectations. This usually stems from the sales stage when salesmen oversell their products by highlighting advanced features that although are achieveable, yet only after reaching a specific maturity level of transformation in the Enterprise that usually comes after a few years of adoption. If you are starting the project after already falling into that trap, the best thing to do is to be absolutely frank with the client about the solution boundaries and limitations even if you think that it might cause disappointment at the first stage, this manageable disappointment is far less disastrous than a failed project after wasting time, resources and mental energy.

Apart from the standard techniques of balancing stability with innovation through prioritization of feature sets and having an agile plan, I would have the client access an agile beta version of new feature sets and have them try it out while maintaining a separate stable release. This helps meet their expectations and also get them to provide feedback on the newer feature sets thus having them participate early on.

The most important thing is to do it agile. Make each release be about a constrained set of stories. Also, establish early in an effective regression test regime and keep it up to date. In general I require at least 2 tests for every checkin and require all checkins to be small enough to read through in under 10 minutes.

Having a customer who likes your product and always wants new features indicates a good product design and implementation process. New requested features give you clear directions to evolve your product and business to thrive. But if changes affect stability - it's a sign that there are problems in product architecture or testing strategy. Architecture should be flexible enough to embrace new ways of implementations in effective manner, it should properly reflect evolvement on business level needs. Proper testing strategy should include availability of an informative abstraction about state of the product and clear meaningful tendencies highlights, that will indicate needs in architecture changes before it becomes a bigger problem.