The only "power consumption balance" issue I can see now, is the batteries won't last as long with the slightly higher powered fan.

The batteries themselves should handle the extra load just fine too.

Though I guess if the wires are already (badly) undersized, running a lot of extra power through them could cause issues, but an extra 300mA isn't that much extra, if they do all draw 1.5A each.

I vote to go for it.