Coug, I had a cravin' for a 7mmX08 several years ago when 'light' rifles first got popular. That was when Brown Precision was building their Mountain Rifles out of M600 Remingtons. I found a cheap M600 with a messed up stock, bought a BP fiberglass stock and had a friend turn the 308 M600 bbl down to 'almost not there' contour. With the fiberglass stock on it, the thing weighed less than 6 llbs.
It was so light I couldn't shoot it offhand very well. So I sent it to a gunsmith in PA that put a 7mmX08 Douglas Supreme air gauged bbl on it with a standard contour. He also put a M700 bolt handle on it. With the new bbl, the beast hangs just right for hunting shots. It is deadly accurate off the bench, too.
About 6-8 months after completing this rifle to the tune of mucho $$$, much more than I had ever spent on a gun, Remington introduced the M7!!! Oh well, at least I have an original...... Since then, I've bought my youngest son a M7 in 7mmX08 and both rifles have killed a truckload of deer. The 7mmX08 is an ideal whitetail caliber.
That said, I have several 308's and I'm not good enough to tell any difference in the two, terminal performance wise or accuracy wise. If that's all you're interested in, stick to your 308. However, you really need another gun :lol: ......and the 7mmX08 is a good one to get!