depends on if the marq is still in good condition, u should probably shoot it first. i have a marq6 and its soo easy to maintain. but i've never shot a trehold yet, so you should try shooting both nd get a feel of both.
i say you get the g3 and save up money for a new board for the 3 shot. there are se g3's right now that have 3shot and a 2piece barrel. also, the colors are sick!! im planning on getting one as a back up. maybe you can lend 100$ from someone? but yea i just think the g3 is better, in love with its cool asa.