I don't know, I haven't done any MTS myself, but at the very least, I imagine it's more stable, and less likely to change it's character much over the first couple months.
Anyways, I went with MGOCPM (miracle grow organic choice potting mix) right out of the bag, and it seemed to work okay. No sifting even. Did get a couple odd twigs/chunks that surfaced after a couple months. Had pretty dark water, but I also had a bunch of wood in the tank. Really extensive root systems when I tore it down.
Just set up another tank, and sifted the MGOCPM this time. it's too new to say anything. I'm just going with the MGOCPM because it's easy to use straight out of the bag, it's commonly available, and quite a few people have used it with good results. I'd probably try to make the MTS if I had more space and was a bit more diligent, but it will have to wait for some later project. If you have access to a clean, non-polluted, non-fertilized area, you can probably just go dig up a couple shovelfuls of dirt outside.
Back to the original topic, what I found works for me is to wet/moisten the soil a little bit before setup. If it's already moist, no problem, otherwise I'll toss it in a container, and then add a little bit of water, and let it sit and soak that up while I go to work or whatever. Then I'll get the tank set up, padded, etc., and set up the hardscape (driftwood bolted to slate in my case). Put down whatever sub-soil stuff you are planning. I threw some dolomite chips in, I think some people do some osmocote. Some people add muriate of potash, but I suspect it's too soluble, and will wash out after a few water changes, even under the soil.
Add in the moistened soil, mush it around and tamp it down a bit, make sure it's evenly spread. Then add the cap. At this point, I usually give the substrate a pretty thorough misting of treated water. Mostly I'm trying to wash the fines down into the lower layers. Then I'll start planting, taking regular breaks to mist the substrate and the plants. Make sure you like the arrangement, because transplanting in a dirted tank is rather messy. Once I get that done, I'll throw in some excess filter sponge, and then slowly pour water onto that to fill the tank. (My current setup has a mattenfilter, and I just added water behind that). I don't get any clouding doing this, and that's using dirty, unwashed, straight-out-of-the-bag substrate.