This looks like a VERY clever device from Hoegger Goat Supply. A pressure gauge is built in so it essentially replaces the crank down screw AND the pressure spring on screw type presses.

http://www.hoeggergoatsupply.com/xcart/product.php?productid=3265&cat=35&page=1

I am thinking about retrofitting my homemade press to get something more accurate than the spring. I haven’t found this anywhere else. Anyone seen or used this kind of device?

I don’t know this device.
May be you can build this one, or with some help from somebody?

I built two of them yesterday. See the finished product in the attached picture (left - not mine). The pressing capacity ratio is 3:1.
The other one (right picture) is my oldest press.