I won a free copy of SysTrayX via DC.com and I thought it was a great program, but after trying PSTray, i was blown away. The interface is simply outstanding, the way it detects tray programs is excellent. Its much more accurate in detecting applications in the system tray. SysTrayX left me trying to figure out why some icons would just not show up in the system tray despite settings I changed, and it also left me wondering why some icons always displayed in the system tray despite my setting the application to hide them. PS Tray has some nice options that systrayx does not, such as the ability to send mouse clicks to the tray icons via hotkeys, or a way to restore all tray icons via a hotkey. Customization is a big plus to me in any application, and ps tray supercedes SysTrayX's ability
One thing that won me over with PS Tray was the authors responsiveness. Upon initially winning SysTrayX, I immediately submitted some feature requests and received a response about 2-3 days later. A few weeks later, I submitted a few more changes (13JAN2006) and still have yet to receive a response to my 3 different emails since that time. The PS Tray author, on the other hand, has responded to every one of my emails within 24 hours and has displayed the utmost professionalism.
And as I said in my above post, another thing that won me over with PS Tray, was their upgrade policy. If there is another version released, it will be provided free to the user. With SysTrayX, you have to purchase 12 month subscriptions for upgrades. With that policy, if you pay and there are no upgrades, you have thrown away money. I am a firm believer in certain applications being on a "Pay once for lifetime upgrades" policy. These types of applications are the ones that seem pretty much feature complete, the ones that might only require an occasional bug fix every now and then. However, other apps are perfectly understandable to be placed on a subscription based upgrade plan. A tray manager is one of the applications that should be pay once since its functions can only be expanded so far.
Anyways, I've said my piece. If you have a chance, try out both apps, I think you will find PS Tray to be a much nicer choice due to its much better UI and the vast majority of options that you are provided with.