As some people mentioned, you're over estimating the number of requests per second for the number of users you have. I would recommend writing a small application to get a feel how it feels to develop on the platform.

I personally found it to be incredibly valuable to be only writing client side code. It let me focus on my end users experience and iterate mich faster. After writing an application on parse, I found myself missing it on non parse projects. I used the parse js SDK to create a SPA.

I did think the on boarding experience could be a bit better. The docs are good, not great. I haven't had any issues with down time but my app is probably much smaller. I would definitely use it again.