I think you make eveything too easy for yourself. There are loads of things you just doesn't seem to think about, like why he writes some things....
First, it says Allegro con brio, it's the slowest allegro after Allegro Moderato. You play Presto. What if he'd written Allegro Vivace? Then you would probably play as fast as you do now, and that doesn't make any sense at all, does it?
Second, The second theme is, for me, way too primitive. I can't hear anything but the upper voice. It looses all it's beauty without the other voices. He wrote loads of string quartetts, so he might have known a thing or two about voicing. And the thirds are dimiuendo! You play crescendo. It's way easier, but not what he wrote. And the sf is just too... There is a crescendo leading to it, your're playing it like there wasn't.
There are a billion other things but, somehow, it's very uninspiring. Think what you do, and why you do it. Obviously you have great technique, but so does everyone else these days. Do achive anything, you have to tell something, and I don't feel you do...