Never seen one in person but they look to have a very shallow V at the transom
As above the 115 is a very small engine for a 6.8m rib however I think they are only rated to 150hp max anyway
I personally would say absolutely no way to a boat like that for $30k
You are right to ask the question though as you may have just saved yourself buying something that looks good but doesn't do the job that you want it to as the design and quality isn't there...
Ribcraft are worth a look but not sure what models you get over there?
EDIT: Looks like you get the whole range, here's a link to their site which should show a video of the 585 doing some turns and you will see how a well designed rib is supposed to handle
(On their website click on the bottom right hand box which says 585 video).