For Appointment Reminder, approximate per-account customer support incidents per month. I've taken the liberty of scaling them to X, where X represents the number for the highest publicly available account plan.
you are certainly right with your scale, but i guess zobzu's point is, that your non-support costs (say: development) is mostly paid by your 9$ and 29$ customers (in absolute terms).
so you cannot just get rid of every customer but your high paying ones.
Good point. Of course it's possible that 7X is a cost that cancels out the revenue from those customers, in which case it would be better not to offer the option, but as long as it's not, it's still profitable to offer the plan. Depending on the ratios, the cheap customer bracket could even be more profitable (in absolute terms, as you say). You just have to build the extra support cost into your pricing.
$9 customer - $5 support = $4 per many customers
$199 customer - $1 support = $198 per few customers
I'm sure the equation still favors your theory, but I'm also sure by a lower number than what you'd like readers to believe.