Some folks that are all into the "you need to wear your kayak" concept might disagree, fine if the do.

I don't do any fast water/white water/surf in my wood kayaks (Sheawater Sport and Chess 17).  I'm 6' tall and 220 lbs with size 11 feet - so I'm not huge, just full-sized...  I purposefully left out the hip side braces in both boats.  I'm sure the cockpit is still plenty strong without them.  I'm very happy not to have the side braces. I don't seem to miss any support, and am happy for the extra room, both to wiggle my butt around and to have a place to put a waterbottle or jacket or whatever beside me.  Also makes it easier to reach things placed behind me and pull them out of there. 

I've got "bike rider" thighs, so I also cut off the keyhole tabs on both boats (so my cockpit is egg-shaped) and put the thigh-top foam right under the rim of the coaming.  I do like being able to brace my thigh tops, I think it helps with extra paddling power.  This larger opening helps with entry and exit with me being a full-sized person. And just FYI - for personal comfort I'm happiest when I put soft things, even an extra towell if I don't have something else to carry, in a small dry bag of about 4-6 inch diameter, placed crosswise in the boat just ahead of the seat - under the bend of my knees.  That helps to keep me keep my thigh-tops up against the braces and makes my whole sitting position more comfortable.  But the bag doesn't get int he way of entry/exit, as it is last in, first out when I'm embarking/disembarking.

   Great. Thanks for the response. I think I'm going to leave them out and if I feel the need add them later. Figure that's a lot easier than taking them out. I was wondering about the keyhole tabas as well but figured get some miles in first. I'm d do surly large and will definitely fill the cockpit as it is. Are you using the seat that came with the shearwater or something else?  

+1 on leaving out that "wear your kayak" junk. I particularly dislike the keyhole tabs  cluttering up the roomy cockpit. Getting in and out easily is the prime consideration. I kinda wish I had left off the foot braces too. My skin-on-frame kayak Folbot (now near 60 years old) has never had them, nor have I needed them. I'm tall and in the Shearwater they tend to be in my way and provide little help even if I try to use them.

   Again, to each his own, but I definitely like footbraces.  I feel they can add a lot of power to your paddling stroke.  If you position the adjustable rail correctly you can always run the foot pegs all the way forward if for some reason you don't like having your feet on them.  While not really convenient (like other braces that have an adjuster unlocking handle that runs back toward the cockpit, as my rudder-braces do in the Chess 17) I've learned to adjust the braces in the Shearwater by using the paddle to press the locking latch, and moving them fore/aft with my toe.  Adjustment should never or rarely be necessary after you find your sweet spot,  unless you share the kayak (my wife and I sometimes swap rides) - and I only have to adjust on the fly when I get all on board having fogotten to adjust before getting in.  I have permanent marker marks on the inner hull near the tracks for the his and her positions.

I have the Creature Comfort seat in the Shearwater Sport.  Yes, it is pricey, but it is my favorite seat.  Good bottom contour, the mesh covering provides a hint of breathability beneth your butt, and most importantly the seat back angle is very quickly adjustable and doesn't ride up or down on your back.  The seat back is just a bit higher than the top of a back-band, I like that, too. The back easily folds down below cockpit rim level if necessary, but I don't transport my kayaks in a way that requires folding it down.

I have a standard kit back-band on my Chess, but put a Hot Seat Grande on top of some of the kit closed cell foam for the seat bottom.  I shaped "cheek divots" into the closed cell foam seat bottom that came with the kit even before gluing the Hot Seat on top - thus my seat is far from "flat" and I think that adds some comfort.  To my memory I had to add a littel extra closed cell foam to creat a base as large as the Hot Seat seat bottom.  I used two strips of big 3" wide velcro (with self-adhesive on the side opposite of the hooks/loops) to mount the seat bottom to the boat.  Thus it can be pulled up or repositioned - but after the first few rides where I moved it an inch or two to find the right placement I've never moved it since.  Sure, this jacked up my seat by maybe 3/4" higher than "normal" and thus my center of gravity, but I've never noticed any stability concern.