Overall, your best money is on the Desktop Connect software. It gives you good freedom to use a remote system at an excellent price. It also offers a few more features than XenDesktop + Citrix Receiver did (like a right click option).
Still, XenDesktop is fun to play with and has its own virtues for someone that wants to get more out of their iPad. Neither option gave me stutter free Flash playback. I was able to get a few YouTube videos to play, but at times they would lag, or time out.
I found that for actual productivity work both of these solutions beat out using the iPad (plus iWork) on its own. There is nothing like being able to have multiple applications open and available when you are working. The iPad just cannot do that, so it is not a good work flow environment.
Still, as you can see, for not a whole lot of time and money you can very easily overcome these issues and add to the functionality of your iPad WiFi regardless of the size.