Benefits would be little to no bloating after a carb heavy meal, better utilization of nutrients, a better pump, fuller muscle, improved body composition and a reduction in blood sugar. All of those are dependent on the ingredients in the supplement. I actually took a serving with my last meal and I still feel pretty hungry despite it being a carb/calorie heavy meal.
There have been a lot of good suggestions in here so far. SlinMax is one of the more comprehensive supplements in this category, along with Recompadrol. SlinMax contains individual ingredients that most people will use to make their own GDA type product which is one reason why I enjoy it.
Na-R-ALA also reduces blood sugar and improves glycogen storage thanks to its actions with GLUT-4 (an important glucose transporter in the body). The dose in SlinMax is a full dose.
Agmatine improves glucose uptake and insulin sensitivity of skeletal muscles.and glucose uptake in skeletal muscle tissue. Agmatine stimulates the release of beta-endorphin that helps move glucose out of the bloodstream and into muscle tissue. Agmatine also helps with a muscle pump. Agmatine also helps with muscle fullness. People often say SlinMax gives them a "food pump", Think of your post workout pump, but just from eating!
Berberine is effective at controlling insulin levels and glucose disposal.
These are the most important ingredients in SlinMax, in my opinion and will help improve body composition, even from those that do not tolerate carbs very well.
I would also suggest using some natural remedies, like adding cinnamon to all meals. Cinnamon tastes great on pretty much everything.
You macro breakdown is highly dependent on the person. Some can function and perform off little carbs while others will fall flat on their face. It is one of those things you need to try and see how your body responds. You could also carb cycle too, which has many benefits. A good ratio of macros people use is a 40/40/20 split of carbs/protein/fat.