Honestly I believe excellent health is more important than the age difference. You take someone like Brad Pitt who is closing in on age 50 but works out regulary, will most likely do well with a 30 year old. If the older person is in great health and the younger person wants what their mate wants out of life then the age difference is not that big of a deal. (Wanting the same things is more important than age difference.)
I've heard some people say, "What would they have to talk about?" However in all honesty it's not like the majority of us spend the bulk of our time talking about things that took place 20 or 30 years ago. Most people choose to live "in the now" rather than in the past. The majority of adult conversations revolve around current events/news, issues going on in one's personal life, movies, sports, or something that came on television the night before. Not many daily conversations are so "deep" that they require an age limit. Not every young person is immature and not every older person is locked in their ways. It's a case by case type of thing.
Awhile back I wrote a hub titled "The Cougar and The Sugar Daddy". In my opinion it seems like women have more of a problem with age differences in relationships or marriages. (Most older guys could care less about a 40 year old or 50 year old woman dating a younger man.) Where as many women in that age group dislike it when men in their age group pursue younger women.