I agree with everything but Sasuke having low chakra reserves. Where does it say Uchiha have low reserves? Sure, he doesn't have the ridiculous amount of chakra that Uzumakis have, but so does 99.9999% of ninjas. Madara is stated to have high chakra reserves. Sasuke's battles show he has a lot of chakra, though not as much as Naruto. Only Kakashi has been stated to have low chakra reserves.
Also, Sasuke does need some power-ups if he is going to be nearly equal to Naruto for their fight, though not as many as were listed here.
Indeed, Sasuke has "strong jutsus", but that doesn't mean he has great chakra reserves... it's just his spiritual powers are high.
If you give a read to the manga in the parts where the jutsu of "Creation of All Things" is explained, you'll note that the Elder Son branch had ninjas which spiritual and mind powers were high, but their body were not as strong as the body developed in the Younger Son's branch.
- The (Elder succesor) Uchiha inherited great Spiritual Energy and low Physical Energy
- The (Younger succesor) Senju inherited great Physical Energy but low Spiritual Energy
- To mold chakra, you need Physical Energy and Spiritual Energy
Deduction... both clans have relatively low chakra reserves compared to the Sage, hence their balance between Physical and Spiritual Energy is disrupted.

it's a very simple logic.
Diagram:
Spiritual Energy: S
Physical Energy: P
Chakra Unit: C
S + P = C
Sage of Six Paths Balance: S+S+S+S+P+P+P+P
Sage's Chakra Reserves: C+C+C+C
Uchiha Balance: S+S+S+S+S+S+S+P
Uchiha Chakra Reserves: C (they only have S+P to mold chakra)
Senju Balance: S+P+P+P+P+P+P+P
Senju Chakra Reserves: C (they only have S+P to mold chakra)
PS: About Madara... well, that's because now he has the balance, since he has Hashirama's DNA to reach the levels of the Sage of Six Path, as well as Obito. But Sasuke... well, he is a pure-breed Uchiha, no more, no less.