At this point you have to think about how you intend to use your boat, trim IMO is the one place where a lot of unnecessary weight gets added to the boat. Gunnels in particular get overbuilt for purpose, with the associated weight gain that goes along with the extra wood.
I trip with my Freedom 17, so weight was a consideration for the build. As far as scuppered gunnels go, they look nice and traditional, but IMO serve no real purpose on a modern tripper, a simple bevel on the inner gunnel will let water out just fine. Capping again looks good, but serves no real purpose from a serviceability PoV .... personally I like the contrast that the hull core makes between the cherry gunnels. I seal the gunnels with epoxy, so there is no issue with water infiltration.
I used 3/8" x 3/4" strips, with a 45 bevel on the inner gunnel, the tops where rounded over (think 1/4" radius) ... these have proven sufficient for task and there is no flexing or other signs of weakness .... you could use this as a reasonable minimum starting point.
Since you seem somewhat weight conscious, lets do a little exercise calculating the weight of 3/8" x 3/4" versus 3/4" x 3/4" gunnels. I will use the density value of 35 pounds/cubic foot for cherry from the Wood Database .... calculate the area of the gunnel (thickness x width) and multiply that by the 4 lengths you will use, convert that volume to cubic feet and use the density to determine the associated weight. The 3/4" x 3/4" yielded a weight of ~9.3 pounds, this does not include the material for scuppering .... using 3/8" x 3/4" comes in at 2.3 pounds, for a net difference of 7 pounds. It is important to keep the weight cost of trim decisions in mind when making those decisions.
EDIT: As Alan notes below, I made a mistake calculating weights, it's 9.3 vs 4.6 pounds for the gunnel weights, leaving the original post intact, so that the posts make sense to anyone reading them. Brian
The decisions you make on the trim have very significant impacts on the final weight, the example above is just for the gunnels, you still have decks/seats/thwarts to consider.
This is a link to my Freedom 17 build, you can see the gunnels in a few of the final pics :
http://buildersforum.bearmountainboa...=2244&start=15
Hopefully, some of these thoughts will be of use.
Brian