Connectivity is huge, but it's only one of the ingredients in making this decision.
If you want the app to work for them outside of the corporate WiFi, you have to host it on the public internet, where all attackers are equally welcome without regard to skillz or skripts. Are you sure that server is secure? What about tomorrow? Are you patching it? Are your users securing their devices properly? Uh oh, it's the new version of Heartbleed, go back three spaces.
You also have to consider performance. Is this something that your users will use constantly for their jobs, or occasionally for some rare piece of info? If it's going to add one second to every screen, and you're asking people to tap their way through 600 screens a day, the inefficiency is going to cost you 10 minutes worth of payroll per user per day. Maybe you make that up in hardware costs if you force your users to bring their own smartphone to work. Maybe the sluggishness just makes your users miserable throughout the day. Or maybe it simply costs you a lot of money.
On the other side, if it's used perhaps once or twice a day by 2000 people, poor performance and connectivity issues won't be nearly as important as savings on developer costs and time to market, Or if you have only a half dozen heavy users, perhaps you're willing to eat the payroll cost of an hour per day instead of spending them on development.
It's a question best answered by the money.