We know he can do high level Kidou with no incantations. We know he can block out Renji attack with his reaitsu, block Zangetsu with his finger, and block Komamura's sword with his finger as well, we know what his shikai does and how he applies that to battle, and can guess other ways he could. And we know he can make GJ fall to his knees just by powering up a little.
Urahara has shown considerable skill but not that much power. He was suprised at Ulq's strength&speed and Wonderwyce managed to get the jump on him and he had slight, slight trouble against YammI(though most likely he had planned to test his Gigai thing against Yammi to begin with). We know what shikai does too and we know he likes to use his inventions to give him an edge.
We know Aizen is most likely stronger than Espada 1 but theres no reason to believe Urahara is any stronger than any VL arrancar, and I doubt he is. Doubt any Shinigami is other than Yama.
I really don't understand how I can say we know NOTHING of the power of these characters. We don't know exactly what they can do like we do Ichigo&GJ but we do have a good general idea.
