Even including those, I don't see how you would get to 8%. Apart from the fact that 'Stripe Identity' isn't something I'd expect a standard SaaS company to need (or a tool like Lago to provide), the cost simply isn't that high. Radar and Sigma together for 1,000 monthly transactions adds like ~$130 to your monthly bill.

I challenge the authors of this blog post to provide me a Stripe product setup that would result in an $8,000 monthly cost for a $100,000 MRR SaaS company. It must be very unusual.

I pay 15% fees because of a very low subscription fee ($2.50).

2.5 * 0.029 = 0.0725 + 0.3 = 0.3725 / 2.5 = 14.9%

They also don't refund fees when a customer wants a refund.

Have you tried encouraging longer subscriptions through steep discounts?

Yep. I offer a yearly plan for $26. My customers are split almost exactly half and half with monthly and yearly subscribers

Thanks for the information; you're probably pretty close to optimal with those prices!