Unlimited? Jeez, that's quite a lot!
There will always be a limit to how many process shall be on concurrently. The limit you're talking about is entry processes.
I believe that there would be less of a limit on a VPS as that should only be limited by the RAM and CPU (yes there's disk space but we're not talking about that nor are we talking about sessions which are completely irrelevant to the question).
I'm afraid that shared hosting isn't really mean't to handle ~300 users concurrently per account.
If you're still wanting to use X10 and decide to go with VPS then you can visit
x10vps.com.
