To be clear, and I'm sure you know, scuds are different than grass shrimp.
I have purchased scuds from goliad and from another supplier (I believe Kyle at Habitat Now but memory is poor). They both were 'scuds' by advertising but I got very different looking critters (size and shape).

Without proper water quality and habitat they may not survive. I tried stocking on a few occasions but none survived. I have no refuge for them as my vegetation is gone (blame the goldfish, the crayfish, or both)

I did try this fall to release a small number of PK shrimp into some areas where I have mats of sedge that fall over and float over the shallows and capture mats of FA. That is the best refuge I have and hoping they will survive and reproduce. Seems like slim chance though. We'll see over time.