I use my tenon jig a fair amount at the tablesaw and at the router table. Mine is similar to yours and was sold by Rockler, is blue, but came with Jet paperwork??? . Still . . . . .
I played around with a dial indicator attached to it at one time. I find the rough scale and sneaking up on the dimension to be more reliable. Similar to measuring off your piece instead of off your plans; small variations and wood movement can be accounted for . You can attach a backer for a clean exit on difficult materials. Handy to have and glad to have it.
This is why I've avoided buying one thus far. I have other ways to make tenons and while they might not be *quite* as easy in volume it's also infrequent enough that without needing to do bulk projects.. it hasn't been compelling.. yet...
Although I will admit Glenn's nifty dovetail trick has some legs on it there!