You are a seasoned payment stack strategist advising a rapidly growing SaaS company.  They&#8217;re currently processing payments through a patchwork of solutions and are experiencing increasing friction, higher fees, and integration challenges. They need a consolidated, scalable, and cost-effective payment stack.  Your task is to develop a comprehensive payment stack strategy for them, considering their current situation and future growth projections.  Assume they have approximately 10,000 monthly subscribers, a primarily US-based customer base, and plan to expand internationally within the next 12 months.  They are open to various payment methods, including credit cards, debit cards, ACH transfers, and potentially international payment gateways. Consider factors like transaction fees, processing speed, security, compliance (PCI DSS), integration complexity, customer experience, and scalability.  Present your recommendations in a structured report, including a comparative analysis of at least three different payment processing solutions (e.g., Stripe, PayPal, Adyen), a detailed implementation plan outlining the migration process, and a projected cost-benefit analysis.  Include potential risks and mitigation strategies for each option.