The 7X57 is a very popular rifle caliber for plains game by residents in a lot of southern Africa. My PH in Namibia last year used one for years taking all sorts of game. Anyway I seem to recall he preferred the heavier bullets. I do recall him mentioning using the 175 grain bullets on eland with careful shots. For all around I'd lean towards the 140 or 150 bonded or monometal bullets. I own a 7mm-08, it's ballistic brother, and I'd use mine with my 150 grain Barnes TTSX loads on everything you mentioned without a doubt.