Wouldn't you? LOL
It turns out that they don't have the same signature. I liked the F1 so much that I bought the MA900 just to see if Sony changed things around...and by how much.
Well, now you've heard yet another opinion.
The signature of the MA900 reminds me of the HD650, while the F1 is like a K702. If you like AKG headphones, you will probably think the F1 is more realistic than the MA900. A basshead will definitely prefer the MA900.
As far as comfort, build quality and sound stage, the F1 is the clear winner here.
Like I said, both are really good headphones. The MA900 might be a better choice with pop, rap and electronic music...with jazz and acoustic music, the F1 is the more realistic and organic of the two.