The process of digitising the risk is browser only, so if that is in your job description you have to use a browser.
Otherwise, it comes down to personal preference. We demonstrate the system using iPads because the experience is crisper: data is loaded before you need it, so you generally don't find yourself waiting. iPads are useful if you are ever off-line: you can carry on looking at the data, responding to chat messages and so on while you are on a plane or in a tube tunnel. Your work will get synchronised when you next have a connection.
We develop "mobile first", so in some cases there's a new function on the iPad that is not yet available on the browser.
Everything we've said above about the iPad also applies to the iPhone. We've worked hard to design a user interface that works on the small screen. That can be a factor in choosing to use iPads - the interface will be familiar to anyone using an iPhone.