I don't know if I'll put this in the right terms, but I think the reason some sighthounds need particular collars is that they have smaller heads in relation to the girth of their necks. Take greyhounds, for instance. If you use one of those collars with a closure the hound will be able to slip out of it. At leisure it should be adjusted so that it sits lower on the neck, but that circumference will easily slip over the head. Martingales are like instantaneously adjustable in the sense that on a loose leash they are comfortably loose on the neck but on a taught leash they get smaller. In the case of basenjis I think you can go either way (sighthound collar or not). Mine wear Northwind martingales.
If you check out All Hounds Apparel, http://allhoundsapparel.com, they have several different styles of collars including what is usually referred to as a Hound Collar. Like MauiGirl explained the traditional sighthounds have narrower heads then their necks so often can easily slip a correctly adjusted buckle collar. Collars like a martingale, limited slip and Hound Collar all make escape more difficult. The difference between the collars I see referred to as "Hound Collars" and martingales and limited slips is the width of the collar is usually greater to help spread the pressure out when the dog pulls in order to help prevent trachea damage.
I love my martingales! I also really like the northwind collars. Kiora has a nice slip collar and a martingale lead from them. I also have a martingale from a lady who makes collars locally. It is really nice beacause they cannot back out of them but they are very wide so they don't cause neck discomfort. One of Kiora's collars is even lined with fleece..comfy! Also IMO The wide martingale's really enhance a long elegant hound neck. The Main thing is just like a slip/choke collar they are for walking only, you cannot use them as your tag collar because their is a risk that they will get caught by the collar and choke.