Today I learned what a hail protector bubble is

I assume the fans are wired in parallel? The new one may run a little faster and/or move more air, but it otherwise shouldn't hurt it, or the other ones.

It looks like all they're doing is pushing air into the bubble?

As long as the power brick is rated for enough amperage to power them all (unless it was super-duper optimized, adding 0.3A draw won't affect it).

I think they just want to sell more motors