minoxidil 5% regrows 50% more hair than minoxidil 2%. if that ratio is maintained, the 12.5% would regrow 50% more hair than the 5%.
At $80 for xandrox 15, you could buy many other topicals that cost much less, like adding green tea extract or apply poly capsules to your minoxidil 5%.
For $80, you could get a liter of linoleic acid and 500mL of alpha linolenic acid.
The azelaic acid does not block DHT production, or at least not enough to affect sebum glands.
The more minoxidil you put on your scalp, the higher your chances of some going systemic.