Closed game is more fun as you actually have to think about what roles there are in the game and wether to trust roleclaims. In an open game it's easy to roleclaim some strong town role and get protected by the doc. In this case mafia members can't counterroleclaim or they'll be lynched the day this happens or the next day. If the claimed townie is lynched first and the mafia member after that it's not that bad, (just a fair trade, one cop for one mafiosi) but if the mafia member gets lynched first
In this game Etch could have openclaimed cop first day. with such a big amount of protectors (toad, mario, daisy) he could have easily made 4 or 5 searches at night without any risk, (just tell them to protect you, day 1->toad, day2 ->daisy, etc.) while mafia were trying to shoot them all.
This results in a follow-the-cop mentality. (meh, i just realize that we had a mafia roleblocker, but there are other examples when an open set up is fucked, look at how i got lamed out of the game as remaining mafia member, i had 0% chance thanks to the open set up)
But in a closed game, a cop claim can mean anything. Has he been trustworthy? Are there role blockers? Are there doctors? Is there a cop at all? Is he the only cop? etc.
In the end i think that open setup is good to learn the basics, see how this stuff works out in practice, but after that it's more fun/balanced to use a closed set up. If the mod actually balances it out good enough.
Edit: Jesters suck in a closed set up btw, way too easy to get yourself lynched when none knows that there's actually a jester. Though i've seen games with some great teamwork between town and mafia to kill the jester at night

Edit2: post 777

Let's go the casino
Edit3: shit, i'm not allowed to edit my posts!