Honestly, unless you find better deals on plated than I've been able to, why not just get jacketed? There really isn't much difference between jacketed and plated for target shooting, but jacketed are more versitile in terms of the velocities you can load them to and are easier to load. The thin plating of the plated bullets can cause problems if you seat and crimp in the same operation, making it take longer to load.
The biggest justification for shooting plated is usually cost, but the price of most plated I've seen lately is about $30/250. Precision Delta and Montana Gold sell jacketed bullets for around $120/1000, which is the same price (but you do have to buy them by the 1000).
As for the question of the sealed base, that is relevant if you're shooting inside (and MG sells TMJ bullets anyway...) but it doesn't do anything for accuracy.