No problem - I should perhaps add that the obvious companion/comparison opening to most of these lines is the Blumenfield rather than the Benko.

In that case some of the 4 Nf3/g3 c5 Nimzo lines would overlap to some extent (They're at least conceptual relatives) with the anti benoni stuff after 1 d4 Nf6 2 c4 e6 3 Nf3 c5 4 g3/Nc3 etc.

I missed this earlier. It seems like an interesting enough idea although somewhat handicapped by white's reluctance to push d5 quickly in a lot of lines.

There are a couple of lines vs 4 f3 involving c5 and b5. (4 f3 c5 5 d5 b5 and 4 f3 c5 5 d5 o-o ^ b5 iirc.). iirc The first maybe lets white keep an edge and the second is plain random.

4 e3 isn't so promising - unless you can provoke d5 b5 doesn't feel too clever. But still several lines after: 4 .. b6 5 Nge2 c5 seem to feature b5 gambits. The main line however doesn't.
(There is even one b5 gambit mentioned in Dearing's book which is prepared with a6!)

Also after: 4 .. b6 5 Bd3 Bb7 6 Nf3 c5 7 o-o o-o 8 Na4 cd 9 cd Re8 10 a3 Bf8 black often uses b5 as a positional sacrifice to slow up white's queenside advance. 

So e3 offers fair prospects to give up a pawn on b5. The remaining lines are however hard.

Against 4 Nf3/g3 white isn't (often) planning to meet c5 with d5 (g3/Nf3 etc instead) so getting in b5 succesfully seems likely to involve having snatched a pawn on c4 first

Finally I truly struggle to believe that any b5 gambits exist against the Samich.

I've probably missed a few though - amazing variety of ideas in the Nimzo.