Sol, Diana, Artemis, and an arbitrary Light SR likely won't be enough to get you through the hardest content in the game (currently Accessory Quest Rank 4, Light in your case). But by the time you get to that point, you'll likely have another SSR. The next SSR you get from Gatcha is going to be a fork in the road for you: whether to stick with Light or to work on a different element with Sol as sub and make it even better than your Light team. Likewise, you'd have to think for a while about how to spend a Miracle ticket.