@quiquito:
I think that it's all about how you see them. Do you see them as an equal, or see them as being younger or older.
I think brother Quiquito has nailed it, so to speak: Age isn't important if the two guys consider themselves equal in the relationship. My last partner was 23 when we met; I was 38. But we respected each other as equals, and even though I was in a more comfortable financial position, we kept that equal as well. It was a fine and beautiful situation.
I might add that "age gaps in relationships," is quite distinct from age gaps for random, probably one-off, sexual encounters. I am flabbergasted by the number of 18-20 year olds who pursue me (I turn 45 tomorrow) with great vigour–they want to "learn" about sex and gay life, both in the theoretical and practical sense. I'm not averse to a romp with a young fellow (as long as he's legal), but with most of them, I have so little in common. I can enjoy an hour or two of sex, but a weekend in my mountain cabin? Perish the thought!