Ask: Webapp related - Free and Paid seperate sites

Hi, I have a web application that is very easy to deploy (php+mysql). It is easy for me to run couple of live sites using this application.

currently I provide free access on my main site. When I have all the stuff ready to collect payments, is it a good idea to direct users to a different domain for paid access.

for e.g Free access remains at mockuptiger.com

and when users want paid access they go to someothersite.com

Users can easily export and import their data from the free version.

Most of the paid sites do offer the free access on the same domain and as part of the same instance.

I want to discuss the pros and cons.

Pros: I can focus on paid users to provide better site performance and support

What are the cons of this approach?

Has anyone done this before?

Thank you Nilesh