I have 3 shrimps in my tank and they live with Discus & Plecos, I have had the shrimps several months, and they seem happy.
I find that you need some type of floating plants, as my shrimps like to hide at the top.
I also have plecos in the tanks, a very defensive L14 Goldy Plec but again I have had no problems.
If you do have plants at the top for the shrimps I recommend that you be very carefull when water changing as I have once found one of the 3 shrimps on my living room floor, thank god I found it in time.
Mells