I don't think the legumes really need to be subbed out. You can get anywhere from 10-15 grams of protein for every 20-carb portion of beans/lentils, and I think this is an acceptable trade. If you need to cut carbs in other areas, then so be it. Legumes are great. With just a few servings of legumes plus an ample supply of nuts and seeds, most people can get all the protein they need. I would cut out all other "excess" carbs completely before I would consider saying no to beans (limit yes, but not abstain).

But that being said, tofu, tempeh and seitan are all good high-protein, low(ish) carb foods.