First, let me tell you that, having a big cock is very pleasurable. A 9 inch is a very good size, and if you add some girth into it, its a plus. When I am with the ladies, and I pull it out, their eyes open up and their facial expression shines. I get so much pleasure from the guy down there that's its incredible.
Getting heads from the girls feel really good too, they can do all shorts of shit when you are well endowed. Also, with positions, I can cover most positions that some men can't, hell, I can cover the majority of positions.
Also, when you are well endowed, girls tend to be more submissive, and I bust a large load too. I would rather have what I have now, which is a well endowed man down there cause I get very good feedback from the girls and my life is also enhance.
When I was in college, I had no money, but I had a lot of girls. Cause, once you meet a girl, she got friends, and she'll tell her other friends, and the next the you know, you got plenty of girls just wanting to see you for you endowment. Lets say, I got my dick suck a whole lot when I was in college
, a whole lot. Hell, I remember during one semester my grades drop because girls wanted to suck my dick so often. So, that's a plus.
I would rather live modestly, as long as I still have all the necessities than be rich and have a small dick. With a small dick, girls will run all over you in the bed and in life. If you got an endowed man, there is more tendency to be dominate in the relationship 
So, from my experience, its way better to have an endowed man and live average than to be a small man and be rich. BTW, 5.5 inch is not average, don't mean to hurt your feelings, but that is a bit small, I think average is about 6.5. Anything over 6.5 is good dick for the ladies. Oh, one more thing, its a misconception that most girls want guys that are well endowed. Believe me, most of the times I am with providers, I am just tipping them and going only 1/4 (1/2 deep if I am lucky) deep in.
If we're talking about a $10,000,000 portfolio vs an 11 inch cock, we'll have something to talk about. Remember, if it's over 11 inches it's not a cock. It's a foot. In any event, I'm pretty close on both of your numbers so there's no choosing to do.