7mm-08 when you run the numbers is just a .308 by a different name, actually the .308 shoots flatter at all hunting ranges out to 400 yards for any given matched bullet weight due to greater efficiency with the larger bore. I've posted .308 vs 7mm-08 ballistic charts on here before and it surprised a good few. With the .25 you can shoot 60 and 75grs for varmint in the mid to high 3000's fps ultra flat, 95grs is just getting way too big to call a varmint rifle. Many of us want an all round rifle for light big game and varminting, and the .25 cal is the equal of the .243 as a varminter and lets face it kills game just as well as a 120 or 140gr 6.5 with 120gr bullets. To many of us, that represents a lot more versatility. In response to your thoughts, my thoughts are 6.5 is an awkward middle ground due to it having only big game bullets with one or two overweight varmint options, and I'd rather go 7mm or .30 cal for more bullet weight if moving heavier, I remain a quarter bore fan.
bigracks, check this out, the work is done for you and cheaper than you could build it for:
http://www.canadiangunnutz.com/forum/showthread.php?893788-Rem-Model-7-25-284-stainless