I would rate the scalability an eight out of ten because you have to do a bit more.

For our last client, we have around a million end users. 

I rate the tool's scalability a seven out of ten. My company has ten users. 

The solution is very scalable. We haven't decided which solution we will ultimately use. As we are in the POC stage, I'm not sure if we will increase usage or not in the future.