Agreed with everything that has been said. When you develop your own interface, please remember the remote buttons available may be more limited than what you have on your just-purchased Roku box.
In particular, many roku remotes do not have the "back" button, nor the "*" (info) button, and you don't have general programmatic access to the "Home" button as that interrupts your channel and takes you to the Roku home screen. The least common denominator buttons available to applications are: UP DOWN LEFT RIGHT SELECT REVERSE FORWARD PLAY.
In particular "UP" is often used as "Back" on many screens. Having many "rows" of buttons where the user is at the bottom row of buttons occasionally makes navigating "back" to the previous screen more of a chore.
Oh and definitely go with double buffering on an roScreen if at all possible. Otherwise your screen will tear.