Yeap the 870(old) / 970 (new) numbered amd cards are often placed on the market to compete with the 70 / 80 numbered nvidia cards and vice versa. it will solidly outperform the gts 450 by a mile at any given time.
So there you go
you got your answer and those performance (non bench tool tests) numbers should be all you need.
You might want to look at 6870 if you are looking for an AMD gpu and if you have the extra to dump in the 7870 is a good choice too especially the DCUs from ASUS.
NVidia however, benefits from better optimization in most games. Thus the higher fps. You also get the extra goodies.
At the end of the day it's up to you if you want an AMD card which is great especially when you are working with images and videos but want to game at the same time and an NVidia (quadro aside) is focused more towards gaming.
Consider a newer card and look for performance results instead of just bench comparison and remember
High end - x930 x950 x970 x990 (replace x with series number ie 4,5,6,7) vs x60 x70 x80 x90
every thing else below that line are trumped by the above-mentioned.
edit : the current and previous generations benefit about 20% - 30% worth of performance at lower power draws and of course new tech.