Wifi Interface and Performance

Can anyone tell the adv\disadv between using a wifi module using a uart interface compared with using the RedSPine wifi module that uses the SPI interface.

I’m creating a board using the RedSPine Wifi module but considering changing the design to use a module like (xbee form factor)

https://www.sparkfun.com/products/11048
or
http://www.digi.com/products/model?mid=4261
or

These module support web server, ftp etc…i assume this would take the load of the main cpu like G120 which i am using?

To properly answer the question, you need to list all of your requirements. Then for each requirement, you can evaluate each alternative for performance, size and ease of development. When you do this, the answer should be obvious.

Performance is not large issue, size an issue, development eas important.

I think i will use a xbee form wifi adapter, give the flexibility to remove wifi if not required and removes the cpu load from the main cpu.

What xbee adapter are you using?