Ok, so here is my SKD Firstspear STT review. I'll apologize before hand that I didn't have the energy to pull out the DSLR, tripods, and sit down at my computer for photo editing. I ended up just used my cell phone and did my awesome photo editing in microsoft paint on my laptop. I hope I can get my thoughts across clearly.
Playing with the STT, I felt it was very light and sturdy. The tube system is just too convenient for putting on the plate carrier or taking it off. The systems using big cobra buckets are probably faster, but they're also much heavier. After fondling it a little bit, I put both pieces of the cummerbund in as far as they could go without having any part of the hook/loop section extend past the pocket in the back as you can see in the picture below.
http://i.snag.gy/K23gJ.jpg
After that, I put it on (very quickly, thanks to the tube system, which I want to mention how much I love again). Note that the plate carrier is completely bare and there is no armor inserted yet. Below are pictures of how much excess room I had inside the plate carrier. For reference, I am 5'10", 160lbs, wear size 30-32 pants and usually buy motorcycle jackets size 40.
http://i.snag.gy/dTHH7.jpg
At least for me, I couldn't figure out a way to get the cummerbund to fit me well. You can't just push the cummerbund sections further through the back pocket because then the hook/loop on one section of the cummerbund will face the elastic or side 6/12 section of the other cummerbund, which means there will be no hook/loop action to keep everything in place.
I am still deciding if I want to keep the STT and modify the cummerbund myself by cutting the thread that attaches the elastic section to the side portion that was designed to hold the armor inserts and removing 4-5 inches on both sides and then sewing the elastic section back in. You can see roughly the section I would want to remove as the red squares in the picture below. You can also see below the cummerbund sections attached to each other laying on the bed next to a Crye JPC and me badly trying to add a picture of the cummerbund section from a First Spear Sloucher. Note that the JPC (which was configured to fit me snugly) only has the cummerbund that barely reaches the edge of the STT tag on the STT cummerbund. The square at the end is hook/loop that goes into the front plate carrier. I think it all comes down to how the STT was designed to take side armor inserts up to 12" long, making this type of design just too big for someone my size.
http://i.snag.gy/mWi7H.jpg
Some other thoughts I have about this carrier is that you will probably want shoulder pads as well as the pig pontoons to help with air flow and comfort. There is no padding or anything else to help with ventilation like 3d mesh. As the cummerbund is also designed hold armor inserts, there are the 6/12 cuts along the outside for you to mount your various accessories, but no cuts on the inside to mount a side armor pocket. You will be able to get a 6x6 steel plate inside, but you will have to rig up something to keep it from sliding around. I don't know of any manufacturer that currently makes side plates that will curve along your body the long end for 6x8 or longer plates. That means you will either lose your ability to mount accessories if you attach a side plate pocket to run say a 6x8 plate standing up or you will need to get a side plate pocket with molle on both sides.
My final thought is that for the cost and features, the STT would have been promoted to my main plate carrier if the cummerbund fit my body out of the box with the rear hook/loop sections simply placed completely in the back pocket. Perhaps if they had used a shock cord adjustment system like the FirstSpear retro-fit cummerbund instead of the hook/loop panels, there would be more flexibility in fitment.