A mobile/android app is also favorable for us because with app we will be in touch with the exchange all the time with only one click. I will suggest the developers that they have to work on it to provide an app for us.
Access on the go, is more essential for any business as per current trends. I believe a light version of yo-ex with common browser, will be doing the requirement of mobility. But creating new an app is not a big deal now a days as lots of developers are available here in this forum itself.
If admin will be looking for apps for android/iOS/win mobile, I believe I could help a little bit on finding good developers and for deployment too.
I thought the site is responsive but I guess it is just the landing page that is in responsive format. If they can't make the whole site responsive I agree that they need an application for mobile. This is for best user experience. Anyway, I find the site good and attractive though I think I am missing something, are there really only four market pair in this exchange?