I think the little Termis look and sound really good on the 821 personally, but it's your choice!
Here's a vid of stock vs Termi on an 821:
https://www.youtube.com/watch?v=qPhKPWxtVOs I think you'll agree that the unbaffled sound is rather nice
I haven't tried the PR5s yet, but I had PR4s on my 696 and they were really excellent. I'm considering the PR5 for the evo next.