One client for ABAP+Java

Hi,

In my PRD system (ERP 6.0 ABAP+Java), users may run via SAPGUI & access cProjects via web. Now I'm wondering that I should whether use 2 clients or just one. If using one client only, should I use client 001 or I can use another I like?

Btw, what are advantages & disadvantages of having 2 clients and the same for using 1 client only?

Thanks,

Toan Do