Is there any way to go online without dual nand. It would be a flashed jtag and I would want to use only the flashed drive online. I am pretty sure it is impossible but I am just confirming that.
Nope you cannot get online with a console running unsigned code unless you want to be a complete idiot and purchase some "online time" from services such as Xbox LIVE "Stealth" and the other wannabe's. If you are using a retail console with a flashed drive. Sure go ahead and play online at will. But do remember there is a risk of being banned from xbox live. You take that risk though.
I would disagree, although XBLS is expensive it is a great service. Especially when you go for platinum. Havent been banned yet and ran the same Keyvault for 34+ days.