I've never had a problem with judos whistling, but I don't use them much anymore.
No cutting surfaces on the blunts hasn't been a problem for me. Any rabbit I've hit solidly has had the blunts go right through them. That includes hex heads, spent shell casings and regular blunts.
Come to think of it, the only rabbit I hit good and didn't get penetration was with a judo - I've taken two with a judo: the first was a gut shot with a head shot followup, the second one passed right through the rib cage.