The “wow” factor matters. Like it, or not, you are in show business. You are an expert. And your firm is made up of experts. No one wants to buy the boutique that regurgitates other people’s innovations. They want to buy the song writers, aka The Rolling Stones.
Scaling a boutique takes money. This type of money is called scale capital. There are three primary sources of scale capital. Each has a set of advantages and disadvantages. Which is best for you is highly situational. And all work well when applied correctly. If raising scale capital makes you uncomfortable, do not attempt to scale. Many people are happy with lifestyle businesses.
The perceived difficulty, or ease, of integrating your boutique will affect your sale. Understand the org model of the type of firms who might buy you. Redesign your model to be seamlessly integrated if bought. This will increase the chances of exiting.