yes you would see a noticeable difference. if your on a 1440p or higher monitor the difference is even more noticable. were talking about a 30-35% difference in gaming fps across the board.
some of the 7970's are worth almost $400 on ebay because of the crypocurrency mining. if you can get near $400 for your 7970, youd be better off just getting an evga 780 acx cooler for about $500. your still getting about a much faster card for only about 100-150 bucks more which is a very good price to performance upgrade ratio.