Citrix Secure Gateway is a product that has been around forever. It serves a purpose very clearly by providing you with a cheap (free) way to secure your Citrix environment via SSL so that users can connect from the outside world. Many small companies chose to stick with Citrix CSG because it allows them to install the CSG on the same server as the Web Interface, and again it’s free.
Now that Citrix is giving Netscaler VPX to anyone with a platinum license, using this new virtual appliance has become somewhat of a no brainer. If you have less than 200 users, the Netscaler VPX should meet your needs just fine without having to invest in hardware or additional license expenses. My only caution would be that I have had a Citrix support engineer tell me that Netscaler VPX was not meant for production, and while many people choose to use it in production — there may be some limited logging and troubleshooting available on it versus the physical appliance Netscalers available for purchase.
If you are interested in playing with the Netscaler VPX, and you’d like to see how to get a free license for 1 year, I suggest checking out the video below. You’ll get a great tutorial on how to deploy it virtually on a Xenserver, which is a great best practice to employ because it will allow you to snapshot the appliance in case you ever run into trouble. The Netscaler VPX is a little more difficult to set up than the Citrix CSG, but it pays off in stability and robustness that simply isn’t offered in the former product.
Naturally, if you have a large farm environment — then the Netscaler VPX will be nothing more than a DEV appliance for you to do your testing and sandbox work on. If you have over 200 users, it’s currently best practice to deploy the physical appliance instead of the VPX.