Anyone using a sizeable hood, what's your fan setup?

So I've got a quote from ventilation direct for a nice 7ft wide sloped front canopy hood...but it comes with a monster grease catching fan (28" square footprint by 27" tall) to mount on the roof.
 
Anyone out there with a hood this size?  Does your fan look like this?
 
(take the spaces out):  http: //ventilationdirect .com/CATALOGCONTENT/FANS/EXH_DU/SUBMITTALDRAWING762.ASP?lprint=1&img=/FanSubmittals/Exh_DU/DU-UL762. gif
 
I'm not charbroiling or frying but I do have a big range with a 2ft flat top and 6 burners.  Do I need this steel parachute or can I go with a wall mounted automotive fan inside my hood?

Try one of these for side vent....I would use this type if thats all the equipment you are running.

Yeah I've got a quote for one of those too but was leaning towards the sloped front for a bit more room above my work surface.  Both quotes called for the same fan though.
 
I figure I could create a side vent with fan for either.  I guess the question is, would the hood filters be efficient enough to allow for non grease rated fans downstream?  Or would I end up with grease running down the side of my rig and grease covered fans ready to catch fire at any moment?
 
 

The question is.... Are you allowed to side vent? If so, I would go that route. I have the "mushroom" on top of my trailer but I have more equipment running and also a busy char broiler that produces lots of grease.
 
I worked movie catering trucks for years, all were side vented with 3 fans. Running a big flat top, ovens and range. We did a weekly wipe down of the fans and the housing, along with cleaning the filters, took about 15 min and cost nothing. 
 
With the top vent, in my neck of the woods they are required to be cleaned professionaly by a hood cleaning company every six months, at a cost of around $300.
 
Did you look at the wall mount fans on vent direct web page?