The T4 is retailing at $2500. The ST-7 looks great, however, it won't even be mentioned to any of my clients untill I have one in my hand.
As with any manufactureer, they always want to show new items at the trade shows to keep interest in the company. That doesn't mean that any of the product will be out by the estimated release dates. One of the best remote processors ever made, their XP-8 was over a year late in being released. Other products just get canceled, RTI's video and audio matrix switchers and Niles' ZR-Pro, to name a few.
They are projecting that the ST-7 will come out at $1800, but there are alot of things that can change that easily. It may very well come in and retail at $2500, just like the T4.
The ST-7 will be reverse compatible with most all of the current processors, just a matter of getting a Zigbee antenna if you are using a 433 one.