I don't think adding 5 hearts would negatively affect the sale of donations. It would be a balanced sale that would take money out of the economy.
I like the idea of adding ranks in general but as Revan pointed out, it would create less incentive to get the pyro+/water+/fly+ donation features to add more hearts to players for a fairly low price (~$50,000). I'm not sure what ranks could do for players in the mining world because there is almost nothing that would create an incentive to buy one. In the nether, even the ranks after "Survivor" some people will just overlook because they avoid PvP in general. Maybe add a cheap rank that gives you a kit of some random mining gear? Maybe a cosmetic rank that removes the "greying" of ranks below Tycoon? Other than those two, I can't really think of anything else but would love to see some other ideas about possible new ranks for the mining world. Also as a reminder to everyone who has issues with dying due to lava/suffocation: Type /spawn. It removes all fire damage debuffs (and obviously stops suffocation).
-1 This would negatively impact the server. As Revan has already said it would decrease the amount of donations to the server. Just buy Pyro+, Water+ and Fly+ it isn't really that hard :/
