It depends on what you want out of the drawer. Some people want a large single drawer they can just stuff with various recovery gear and a fridge slide on top. You would end up with more total drawer space in the drawer and you would have one less slider (~7lbs). I thought about that, and it was an option that was discussed. I decided to go with the parallel dual drawer. One for locking items, and another misc/galley drawer under the fridge. Because the X doesn't have a tail gate, we found that the thing we wanted most was a slide out counter top for those stops to make lunch or just putz around without having to unpack a table. Now we park, lift gate opens, the fridge slides out, and the counter top and drawer slides out from underneath the fridge, and I have a table/utility space. Or for discussion over a map, or whatever. It was a utility/feature I wanted that was more important than just the raw cubic inches of the drawer interior.
You could save weight by only linex'ing the exterior. I will line x the whole thing for durability and asthetics. Bottom line, to do just the exterior looks a little cheap imo. With drawer systems this expensive, people expect to see certain things...like the whole thing coated...same for the tbar locking handle. I could use a simple drawer pull and cylinder lock instead, but thats not what people 'expect' to see on a drawer system of this caliber/expense. Call it vain, and it is a bit, but its just a reality...and to be honest, I'm one of "those people" with that. The "gucci-ness"/fit finish/appearance of the system matters quite a bit to me. Vainly/put bluntly, I want people to see this drawer system and say "man, that's a sweet system" not just "yeah, that looks like it works."
That's the thing with the drawer setups that can make them kind of tough to please everyone. Everyone has different wants/needs for the system. As you mentioned, you may want a larger single drawer for more drawer space. I wanted some specific utility I saw from his LandCruiser system that took care of a headache we had on trips and added a ton of utility in an area we really wanted to have it.
The tolerances this is being cut to are borderline absurd. There isn't one single cut that isn't measure to the 64th of an inch or one angle that is the slightest bit off of 90deg. It is cut and fit perfectly. I am really impressed with the craftsmanship. Not to say other systems made by other folks don't work for their needs, its just a different level of quality. This truck will likely move with us to Africa in a few years, so having everything built to standards is important now.
As far as OME-
I would take a ride in mine with the HD set up before you commit to the medium duty. You aren't that far from me so you could shoot up when the drawers are done and see the whole set up. The HD suspension is not too stiff IMO, and I would probably feel the med duty is too light...especially if you add armor. $.02