
The more that I think about it, the more I'm inclined to think that all of the blade runner unit are replicants. Really, now- who is a profit-obsessed society going to send after these superhuman replicants: human beings who can sue to city from hell to breakfast if they wind up like Holden1, or vat-grown beings who think they have that prerogative?
Please note that there are two reasons for not giving the blade runners capabilities equal to those of Batty and the others: for one thing, you want the blade runners to think that they're normal humans, with an investment in stopping the replicants. For another, the replicants themselves (at least until they visit Tyrell) really aren't that much of a worry: some property damage, and a few minor deaths, but it's not as though they're sabotaging the safeties on a fusion reactor, and turning half of the LA sprawl into fused glass. (Batty-class replicants, we may assume, are far more expensive to turn out than replicants with the capabilities of a normal human.) Grow a few more blade runners, have someone like Bryant mumble a few words to them concerning their (spurious) mutual past, turn them loose, and reassure the stockholders that the problem is being addressed.
Gaff? He's the replicant who figured out what's going on: a few misentered keystrokes on a computer, or some such. He's seen his own death date; at this point, he's simply amusing himself. (It's a good bet that Deckard isn't the only blade runner receiving those origami dream symbols.)
1Holden himself was a sacrifical lamb, used simply to give the company an opportunity to test the Voight-Kampff apparatus; after all, they already had a perfectly clear image of Leon, who appeared at the interview using his real name.