There is general agreement that under Price's leadership, the raid stood no chance of any lasting success.

The bigger question is whether under better leadership the expedition had a reasonable chance to win a significant success and stay in MO. I think the answer is clearly no.

1) Success had to be predicated on some spontaneous mass rising of Missourians. Price got some recruits, it is true, but no mass rising. And it is odd to think that southern sympathizers who had stayed out of the war for 3 years were going to suddenly enlist at a time (1864) when the Confederacy was obviously losing the war.
2) Even if the mass rising had taken place, the Confederacy had no means to arm, equip and supply the army in MO. In reality, Price didn't have enough arms for the recruits he did get, hence the unarmed brigade at Westport. Even suppose a Price army recruited to 50,000 men somehow--how could that army be supplied by the Confederacy in MO? Wagons from Arkansas? Ships up the MS River?
3) Price's army wasn't strong enough to win any decisive victory. Remember, it started off with at most 12,000 men, many reluctant conscripts, up to 1/3 of the men ill-armed or unarmed. It had only 14 pieces of artillery, the normal artillery component for one division. In reality, it wasn't strong enough to seize Fort Davidson or Jefferson City, let alone St. Louis.