Enterprise Architect with 20 years of experience in helping companies successfully achieve strategic transformation using technology.
Clarity about the requirements of the service design should inform how you select the best platform deployment model now and in the future.
The Service Design should encompass 1) Availability Requirements, 2) Performance Requirements and 3) Scalability Requirements. Availability Requirements can be expressed in terms of acceptable number of downtime hours per year, Performance Requirements can be expressed in terms of maximum required transactions per second, and Scalability can be expressed in terms of the degree of linearity in adding additional peal transactional capacity to the system.
Implementing these service design requirements using a PAAS approach will require having significant technical expertise on staff. A different and more flexible option to consider would be to use an infrastructure-on-demand approach as currently being offered by Amazon Web Services (AWS).
AWS would allow you to deploy your preferred technology stack at an initially smaller cost commitment level and then scale up both the transactional capacity and redundancy as the build out of your business model warrants.