I am definitely a fan of movement between JO/Xcel. My DD went from Xcel to JO a few years ago because she wanted a more intense program, and she very happy that she took the leap. From my perspective, it's not really a question of being "worth it" or not. For most gymnasts, "going further" doesn't mean much. The real takeaways are lessons regarding teamwork, tenacity, friendships, sportsmanship, physical fitness, etc. So I would suggest looking at what your DD will gain/lose from such a change.
How will your daughter feel about being older than the rest of her team? Keeping it real, without a ROBHS, she's technically not even ready to compete L3 (let alone L4), and I assume the L3 team is about age 7-10 based on your post. Does she have a kip? Pick up skills fast? The friendships and social aspects of team gymnastics are critical to my DD's enjoyment of the sport, so this would be a big consideration for me.
Will she be OK giving up the optional routines of Xcel for more tedious compulsory routines?
Will JO require more gym hours that could impact your daughter's ability to participate in other activities, complete homework, etc? Increasing demands (school and social) seem to particularly impact gymnasts during their pre-teen / early teen years.
Will your current gym allow your daughter to move to JO? Or would it require a gym change? In our case, DD's first gym did not allow mobility between the two programs so her move to JO also meant changing gyms. Along the same lines - If your daughter moves to JO and doesn't like it, will the door to Xcel always be open to her?
I'm sure there's more to think about, but hopefully this gets you started. Good luck!