Good news is, whichever you chose is likely to have a positive outcome. Boys have lots of time to learn, mature, polish, often repeat, and still have great success
I have a new L4 this year (DS7), and a year ago when he was turning 6, I was originally disappointed when I figured out our gym would keep him (and others his age) on pre-team another year when he technically had all the skills to compete L4. I was excited and anxious for him to compete, and waiting another year felt like a waste of the time he had already put in. I thought he looked pretty good!
Fast forward a year, and he looks SO much better in his form, and now this little team is likely to have a shot at some podium spots. AND he is unlikely to have to repeat L4 next year, already working on L5 skills. AND I saved a couple thousand dollars in tuition and meet-related expenses, so I am now actually completely supportive of our gym's philosophy.
In your case, not knowing your gym's general philosophy, I might push toward competing if:
- He indicates interest (even if he's nervous - they pretty much all are)
- Other boys he has been practicing with / is friends with his age are going to compete
- He has the minimum routines already and will be bored if there is nothing new introduced in pre-team
- He is on the mature side for his age
- The extra cost doesn't create strain for you
- It is common at your gym to compete as a 6 year old and repeating L4 is a normal path (i.e., he wouldn't feel bad if he had to repeat) Not that he definitely would, but repeating is common other places when you start at 6.
Just my thoughts. Whatever your son, you and coach decide I'm sure will work out for the best!