I would have assumed that some of the TL15 items that are now part of the recent upgrade in 3I warships from TL14 to TL15 were the result of Imperial research conducted at such a station.
I also imagine that the work being done in these stations takes probably 10-20 years to filter down into new products, as they are implemented into designs, tested, and then mass-manufactured.
Reading over the old TAS entries from the CT era, you can probably find a number of mentions regarding experimental ships, etc. In DGP's Grand Census and MT, the increasing presence of neural sensors and neural weapons indicate that such work has entered the mainstream.
It's a slow process, and not readily visible, nor do I feel that it should be. These things take time, and we typically only look at a small slice of the timeline, so we don't get to see frequent additions and updates. Sadly, Imperial research doesn't all get released every ten years at some "Imperial Technological Advances Parade," probably for security reasons.
You can see the overall impact of such releases when you look at a bigger swath of the timeline. Consider the Imperial average TL 14 of T20's primary Gateway Domain era, compared to TL 15 of the CT/MT era. Hope this helps...
My two Credits, anyway,
Flynn