I tend to hate sites that push an app on you. Who wants an app for every forum they visit? And I know mobile themes are well intentioned, but it seems like a majority break some important functionality of the desktop website. Most of the time, if they provide a link to bypass the mobile theme, I use it.
I've been on android for awhile. With Opera Mini before I got my new phone that runs Chrome. I think the future is about mobile browsers that can better handle desktop sites, and probably also websites better designed for either type of user.
So if it were me, I wouldn't waste a bunch of time/$$$ on any app or mobile-only themes.