You can't have Fillion as a Ghostbuster!! this is suppose to be a bunch of quirky, wacky, regular Joe oddballs that don't look like movie stars, they look like blue collar workers doing a mundane job. Fillion is a good looking heroic young
Han Solo type guy, that's not the type of guy for this film jesus!. Its not about good looking buff blokes running around with gleaming white teeth and being generally superheroic, may as well cast Cruise, Pitt, Depp and Clooney if you want that. Glad some of you don't make big decisions
Same goes for having a female member, that would inevitably bring along the cliched sexy Ghostbuster angle with tight outfits and lame feminist gags. Plus you know they would use someone like Megan Fox to attract all the teen males.
Maybe have a female join the regular four during the film as a recruit which two of the team have reservations about...kind thing, but not one of the four.