In professional services (paychex SOW contractors) there is a relatively low skill ceiling for engineers, even if your team is working on the new stack (Spring Boot microservices, kafka). There's always a chance that when your project wraps up you will be reassigned to a maintenance project on a product that's a dead-end from a technology perspective.
The culture is not engineering driven. Career path for engineering-focused developers is towards solution lead and solution manager, but these roles seem to provide fewer opportunities for developing engineering skillsets. All upward paths lead to management, away from tech. Maybe not a con for all, but a SOW team is not the place to grow as an engineer after the first 1-3 years of your career.
The health plans are equivalent to having no coverage at all if you are a remote worker living in any state other than NY. Moreover they offer an HRA instead of an HSA, the latter of which would be way more advantageous for many employees. You can decline the HRA and contribute to your own HSA but the employer will not contribute to your HSA as they would the HRA.