No question: Low-carbohydrate diets generate improved postprandial lipoprotein responses.
Here's a graph from one of Jeff Volek's great studies:
Participants followed a low-carb diet of less than 50 g per day carbohydrate ("ketogenic") with 61% fat. The curves were generated by administering a 123 g fat challenge with triglyceride levels assessed postprandially. The solid line represents the postprandial response at the start; dotted line after the 6-week low-carb effort.
Note that:
1) The postprandial triglyceride (area-under-the-curve) response was reduced by 29% in the low-carb diet. That's a good thing.
2) The large fat challenge generated high triglycerides of greater than 160 mg/dl even in the low-carb group. That's a bad thing.
In other words, low-carb improves postprandial responses substantially--but postprandial phenomena still occur. Postprandial triglycerides of 88 mg/dl or greater are associated with greater heart attack risk because they signify the presence of greater quantities of atherogenic (plaque-causing) postprandial lipoproteins.
A full discussion of these phenomena can be found in the Track Your Plaque Special Report, Postprandial Responses: The Storm After the Quiet!, part of a 3-part series on postprandial phenomena.