I would not assign much value to portability until the conditions are clear. It may depend on approval for the next property, the new loan-to-value and any change in borrowing amount. Treat it as conditional flexibility, not a guaranteed escape from early-repayment charges.
I’d also ask for independent evidence of what the service produces, not just a polished description. A redacted sample planning pack could show whether its budgets, task assignments and unresolved issues are genuinely clear. References may help, but the relevant comparison is a similar New York...