We don't have rotation and lateral acceleration figures for the MSR yet, so comparisons to other medium ships seem a bit early. It's quite possible it is as fast as a medium ship, but does not turn well (like the 600i and Carrack). That would end the comparison to medium ships like the Cutty and Lancer.
Presuming it does handle like a medium ship, I think you'd still rather have the Cutty to fight with. Not sure what will become of the Lancer. Surely though in a conflict, the MSR needs to run away from almost anything. If you're not comfortable running from conflicts, it's not the ship for you.
Note too, the hidden cargo area is not so far as I'm aware, an addition to the 96 cargo, and out of that 96 total, you lose about half if you put a rover in. People are going to be very disappointed if they convince themselves this ship can do everything better than all the ships it competes with, including the Connie and Corsair. Despite what the ships page says, this is really a large ship built with medium components, just like the Connie and Corsair. That's where the best comparisons lie.
Why choose a large ship made with medium components, when the large components like those on the 600i give such a bonus? I think the best reason is if you're interested in stealth. There are no Large stealth components.
It remains to be seen if you can run this on a pair of Eclipse, and what the EM sigs will be. I'm hoping this is a great stealth platform, but right now, no one knows.