Right now, there are 13 infiltrators on EC, 9 on Dwilight, 21 on Beluaterra and 14 on FEI. I don't have access to Atamara on the Colonies.
In my opinion, these are reasonable numbers. The class is viable. We wouldn't want or need so much more infiltrators.
That doesn't mean anything. I've had warrior/infiltrators who never performed any infiltrator actions whatsoever, because they didn't have the time and gold to spend months training and that without the training the actions are too risky to be worth it.
The number of total infils does not equal the number of infils on duty.