Dave - you get my nod on this one - regardless of which "herbicide-grade" surfactant one might use.

Sorry to speak my mind on this issue; but I have to disagree with some of the above posts.
Dishwashing soap is mostly detergent, with only a small amount of ANIONIC surfactant - BTW, the high-foaming type. In only one aspect does the diluted surfactant found in "soap" serve a similar purpose as the NONIONIC surfactants used for herbicides; which is to decrease the surface-tension of the detergent/water mixture for better coverage and cleaning of dishes or clothes. However, the minute amount of surfactant found in soaps does little or nothing to aid herbicide leaf-cuticle penetration or reduce droplet-deposition evaporation-rates (both functions are offered by a good commercial surfactants intended for herbicide treatments).

Truth be known, there are huge differences found even in the "herbicide-use" surfactants. In general, the less expensive surfactants (aka "cheap") are cheap for a reason. Even if they're marked as a 90% "active-ingredient" (and therefore contain 10% water), the 90% a.i. is often comprised heavily of IPA (isoproply alcohol) and other glycols, which may be detrimental to herbicide performance. In short, check the product's MSDS and key-in on the flash-point. The lower the flash-point, the higher the concentration of IPA and other volitiles (flammables) and the less beneficial it is deemed for herbicide performance.

Like so many things these days, you seldom get something cheap that's "good". But, (in the next breath) just because a product is relatively expensive doesn't mean that it is "good". Cutting to the chase: Chemical suppliers will usually have multiple formulations of surfactants under different names. They have "cheap" surfactants for folks who shop on price (yet the supplier probably make more profit on these lower-priced surfactants). Suppliers also have "good" surfactants that cost more - but, usually for a very good reason. Enough on that....

BTW - diesel makes a terrible surfactant (IMO) for systemic herbicides (whose mode-of-action entails being absorbed and translocated within the plant's vascular system). Why? Because diesel will rapidly dissicate (destroy) the very leaf tissue that is vital for the herbicide's uptake. Oh, granted, it looks good to the uninformed user - because diesel-treated plant withers to a crispy brown within 2 to 6 hours - especially during hot weather. However, systemic herbicides usually take days or weeks to execute their functions on the plant. But, when the plant "browns-out" in hours, the plant's physiological activity comes to an abrupt halt - as does the herbicide's movement within the plant. Basically, if you're going to use diesel in your spray-tank (specifically for foliar treatments), save some money and skip the "herbicide additive".

Lastly, INERGY is produced by Estes Inc. It is a methylated seed oil (MSO)+ organosilicone combination. It works exceptionally well with many herbicide chemistries - particularly HABITAT. However, some herbicides will perform equally well with "good" conventional non-ionic surfactants.