if you're looking at a makerbot 2x - which is well under your budget and a much smaller print volume.
Then you'd be better off looking at a flashforge creator pro (basically an upgraded rep2) or an ultimaker 2, or one of the new ultimakers they launched at ces.

All printers can do 100% infill. And you DO want opensource software. Because that gives you a wider choice in the software you can use to generate your prints.

At the top end of your budget the basic hyrel model creeps in. Industrial quality and the option to add different heads for different material in the future.
Plus hyrel do a training virtual hands on session before you pay them to make sure the machine is right for you. As far as I know that's unique for a machine in the sub $5000 market.
Plus I can't see any plastic parts in the videos.
http://www.hyrel3d.com/

The other way you could go is buy 2-3 flashforge creator pros. thats way you multiply your production ability and have back up should one go wrong.

Or spilt the difference and go the ultimaker route.
https://ultimaker.com/en/products
They keep winning best printer awards and have larger build capacity than the makerbots. And opensource software - it's a good thing ! lol
I believe they've just set up a usa distribution centre as well.