Don't underestimate how much strain newbies put on their bikes, especially when you consider that most newbies haven't learned how to be smooth yet. So, landings are harsh, bails are more common, and properly maintenance may not occur. This leads to a good chromoly bike being trashed pretty quickly by newbies.
An aluminum racing bike would be torn to shreds in just a few weeks.
Aluminum racing bikes (or flatland bikes) are made for that exact purpose. No serious jumping, no harsh landing, NO GRINDING! You can take an aluminum bike out for an infrequent street session, but it should not be your regular ride.
If you plan on NOT racing, then definitely go with a decent 4130 bike.