Keep practicing but be selective about when/where you do it unless you're extremely comfortable...AND quick enough at unclipping to not eat it into a lane of moving traffic or other riders. I trackstand at every stoplight on my way to work and home each day, most days never putting my foot down between pushing off and rolling up to my destination. In group rides however, I usually unclip because others have no idea how in control I am and would likely be nervous, plus it feels too much like showing off and would likely be taken as such despite it's other real benefits.
Oh, and it doesn't require an uphill, although it makes it much easier. With practice you can 'bounce' your balance point off of your front brake instead of an incline, but this
can reduce further the appearance of being in control, but can be fine tuned with even more practice to help with that.
I do it for a couple of reasons. It's much easier to get a quick start at a green light and clear the intersection, AND just as importantly it gives me something to distract myself with during the red light waits. With practice you'll be able to swivel your head around, check for traffic behind you, and watch cars go by etc. without losing balance. It truly is a fun skill to master. Happy practicing.
I learned on a Mnt. bike years ago and when I got started with road it realized how much easier it was. It was years later when I had the opportunity to try it on a fixed gear bike, and wasn't really comfortable with it. The technique is very different between the two, and moving from one to the other requires some adjustment. I suppose some other past interests of mine may have helped me with the balance part...but who's to say...
-Jeremy
