Light for caliber bullets are a bad idea..
Everyone has had different experiance in bullet performance. A lot of shooters that use the 30-06 like 150gr bullets. To me that is a little light, I always shoot 165gr Ballistic Tips or 165/180gr Partitions and have never had a issue with bullet performance after it hits the animal. If it was my new 7mm mag I would load up some with both 150gr and 160gr bullets. I would think that the 160gr bullet weight in a controlled exp type would be the choice for Elk.