The key difference between Heroku Connect and Salesforce Connect is Heroku Connect synchronizes records between a Heroku Database and Salesforce (a copy of the data is kept on both systems). Salesforce Connect doesn't keep any of the data locally (good for your data limit). Unless you need Salesforce Connect for the previous data saving or data residency requirements Heroku Connect is just as suitable. Although I think in this case it's just an example don't overthink it :D
