What are some pros and cons? Do you have any first hand recommendation or experience you'd like to share?
hire them as full time employee with hourly rate, and do performance evaluation monthly
Some thoughts,
Milestone basis is good for planning ahead your development budget. In my case decision point to take this approach is how well you define your milestones. If the definition of done is detailed enough you can go with it, else it will leads you to headache when wrapping up the project for payment since the mutual agreement on what the milestones’ outcome are not clear.
In the other scenario where you choose to scale the hourly basis approach, as the number of developers grow, your project management skill need to be grown to maximize your resources. Else the P&L will bad and in the future the revenue per developer will be low.
So, depend on your current situation, the answers will be different. There are no one solution that fit all.
thank you for such detailed response