1. The Subversion ability suffers greatly because you have to get your ship near to the planet to cast it. The Sova, on the other hand, can cast from far away and run around the gravity well, jumping out when needed. The Marauder has much less survival probability since it has to get in close to use Subversion. Nevertheless, if you want to take a risk, you can lead with the Maurauder and send in a starbase builder. If the enemy doesn't have a fleet, that subversion can stop the enemy from building enough frigates to kill the starbase while it's building.
2. In an eco spot with Vasari Rebels, the Marauder opening is a nice gambit for later game play. Build the Marauder, upgrade it with credit purchases as fast as possible, and then work toward that level 6 ability along with jumping starbases tech. You can, at the cost of some eco support for your team, get tha jumping starbase up-and-running and effective in fairly short order. This can be enjoyable, if risky (i.e., you're assuming that the rest of your team does not die from a weak eco slot while you're on a joy ride).
So the Marauder is a potentially interesting choice as a starting capital ship to juice up your life now and again. The problem is that it's a risky choice (compared to the ever-so-reliable Egg) so it should only be taken for a joy ride when you feel your team has some kind of advantage based on the 5v5 picks that were made.