It's a short but interesting concept.
Level 1 Reimu has an obvious advantage in the early start compared to Level 1 Youmu, especially for the second stage.
Level 4 Youmu has decent dps compared to level 4 Reimu.
Marisa's dps isn't really worth the high cost of purchase and upgrading, but the slowdown effect of Alice can come in handy.
I'd love to see the concept expanded in the future.