You're getting a very good deal. The .30-06 and .308 are very similar with a slight nod to the '06. A deer is never going to know the difference. I have never loaded for a .308 but the '06 can be loaded from 110s(Maybe lighter?)up to 220s(maybe heavier?) I love my .30-06 and it has done everything I've asked of it out to 400 yards and this year hopefully farther. However, I don't think it really fills any gap for you... still a great buy, but very similar in real world application to what you already have.. I'll never be without a .30-06 though. If I had to cut down to 1 rifle it would be the '06
-Jake