The 6.5-06 is an excellent wildcat. I had one years ago and enjoyed it very much. In my opinion it has a lot more going for it than the .25-06. I played with various 100, 120, 125 and 140 grain bullets. I found the 125 grain Nosler partition bullet to be a great performer in the 6.5-06.
Actually the 6.5-06 is a very old concept. It first was brought on the scene in 1913 by Charles Newton. It has also been called the .256 Nieder. I've always thought that both the .25-06 and the .270 Win. were second raters to the 6.5-06. I took quite a few antelope using the 125 grain Nosler partition at about 3150 fps. I hope that this helps.