The only time I think I'd be even slightly reluctant to stack off with the AKs would be against a tight opponent on a paired board. Otherwise I am looking for the best way to get it in - Whether it's C/R or B3B. AQs I am slightly more careful, we may have only 12 outs (and we must discount a few of them anyway) but even then its pretty rare I'd be doing anything other than shipping.