Agree that a lot if silver doesn't magically increase sensitivity. If it did then old silver coins would form pictures on your pockets.
If you don't like the flat look of "normally processed" T-grain film And you really need superior sensitivity then I would suggest that you should look at alternative processing for the T-grains to give you the contrast you're seeking.
Right off the bat continuous agitation will drive the contrast up.
And a whole lot of folks really like the character of the Fuji T-grains of you just can't stand the super linearity of T-max.
For some reason Ilfords Delta 400 doesn't get the respect that I think think it deserves. You might try it too.
But in the end, as much as I like Efke 100, it isn't a low light film. Underexposed areas just turn out blank. No matter how much you over develop.