I've had to do it before, and it really is a million times easier to just remove decor and livestock, then drain the tank and switch substrates, and fill it back up, adding livestock and decor back in. I didn't suffer a single loss from the process, and it gave the tank time to settle with the new substrate. I'm not sure if fluval stratum does this, but some substrates require a period of time to sit in the tank without livestock - they release ammonia when first added, so it is unsafe for fish or shrimp to be living in the tank during that time. I suggest you research this, and decide whether it is the right substrate for you. You could just as easily go for an inert gravel or sand, and that will be pretty much as good for the neos as stratum. It's meant specifically for well planted/aquascaped tanks and caridinas, and in my opinion is not worth the price.
If you were to go with that substrate, and not remove any livestock, I would personally set about it by removing the substrate either by hand or with a small aquarium net. Be extremely careful of the shrimp, as shrimp can sometimes be a bit dumb... usually not, but it's better safe than sorry. Once all your substrate is removed, wash your new substrate very well, and slowly add it in with a cup or something. Don't pour from the bag - again, crushed shrimpies are not happy shrimpies.
Good luck!