As a startup expecting to double headcount, which CRMs scale best in terms of features and pricing without needing a complete re-platform?

We ask the same underlying question in different ways.

• As a startup expecting to double headcount, which CRMs scale best in terms of features and pricing without needing a complete re-platform?
• Which CRM tools offer a smooth upgrade path for pricing and features as a company grows from a small team to double that size?
• Can you recommend CRM software that offers flexible pricing and feature upgrades designed for teams that are rapidly expanding in size?