Viking V65 vs V70

I am just begining research into the purchase of a new or slightly used viking V65 or V70. I was wondering if anyone out there had an opinion on the differences between the two. I wanted to get my "ducks in a row" before i am inundated with salesmans pitches.

I was also interested in a comparison of the quality (seakeeping and fit and finish) of the viking vs other express type yachts ie pershing, sunseeker etc.

Thanks a million