I have noticed no negative effects whatsoever from adding the clock, changing to better fonts, having the right joystick change pages... I highly recommend customizing your reader - if for no other reason than to lose the fear of bricking your unit
(I've bricked it and unbricked it a few times already). But seriously,
you only run risk of bricking it if you change the fonts incorrectly - not by using the excellent script changes. Try them - you will never go back. The clock is subtle only a glance away - SUCH a help to me.