I'm not sure I can answer this for you - but I can tell you my experience with Bailey.
I got Bailey when she was a puppy. I had a lot of anxiety during the first few months. Even after all the research I did before getting her - I didn't fully comprehend the responsibility until she came home (i.e. potty training, early a.m. trips to potty, the complete disruption in my life), I felt a lot of guilt leaving her at home while at work, and the vet trips the first year were expensive.
Of course, all is fine and I'm sooo glad we had the exprience together. I just wasn't prepared in the beginning. I'm not sure if getting an older dog would have relieved any of the anxiety?
Now, Bailey is completely in sync with our lives - she's the perfect match for us.
I'm even considering getting another one!!!