All "net" carbs do is subtract the sugar alcohols out of the total carbohydrate count.
What is important to watch and remember is that Sugar Alcohols have a low impact, not a zero impact on your blood sugar. Some sugar alcohols affect your blood sugar more than others. The best thing you can do is research various sugar alcohols and read labels. Don't forget that the first things listed have the larger amounts of that ingredient in the bar.
Personally, I think protein bars are kind of a waste. I do think that they are better than nothing, but there should be a way to get some sort of supplemental protein into your diet. Drink a shake, eat some turkey, etc.
I just started making my own homemade beef jerky out of venison. It is basically sugar free other than the 1g of sugar that the Lea and Perrins Marinade has.