Hey there,
Great question. So there are a few ways to think about this:
1) Do you have insight into how many of their clients are finding them through Homestars?
If it's delivering new leads (which is what most small businesses are looking for with online review management services and general digital marketing services), then it's important to see how that may have changed over time and to propose how adjusting their review response along with developing their positive reviews could increase the leads. Propose it as a pilot program and if the strategy is effective, they're more likely to be willing to 'double down' on Homestars review management.
2) If they're not seeing prospects coming from Homestars, then there would be more value in proposing to work on their Google review portfolio. That is going to have much more visibility and result in more potential customers finding their business (but not as targeted as a Homestars prospect). The value with the Google reviews helps as a local ranking factor, but you're also casting a bigger net.
The key with either strategy (and something highlighted in the article) is being able to show where new customers are coming from and making sure you can accurately help the business owner see the value of these various channels. If you can help them set up call tracking (via Google My Business) or contact form conversions (via Google Analytics) then you can better show the value of your other digital marketing efforts.
Now it's important for you to do your own research as well depending on your client's industry and location. Homestars seems to be ideal for professional home services in canada. Do prospects also look to Yelp, Thumbtack, Home Advisor, Angie's List, Facebook?
Here's our full list of 3rd Party Review Sites (with additional industries):
All Review Sites Monitored or Linked by Grade.us | Grade.us
Ultimately a platform like Grade.us is part of a holistic local marketing approach that will help you develop a positive review portfolio that will help diminish the impact of negative reviews while casting a wide net (more open less targeted prospects on google vs. hyper industry focused prospects that are doing their research on Homestars). The analytics part will help show the result of investment on whichever channel you're helping the business owner develop.
Is that helpful?