After studying various discussions of the "best electronic hearing protection" I decided to order a set of MePaBlu muffs.
see here for background.
iShot was selling them, but said they were sold out and backordered, but now don't list them at all. Through the BrianEnos (pistol shooting) forums, I found this guy who sells them:
He had a pair in stock and they are on route.
They look good. I'll play with them and post a review.
I picked these over the Sordins because they kill more noise (the Sordins don't really have a very high noise supresion rating), and the MePaBlus look more comfortable. For what I want (mostly USPSA competition pistol shooting) these seem better. The MePaBlus have a Noise Reduction Rating (NRR) of 27 db (which is about what I want), my current non-electronic muffs are rated for 30 db and I always use plugs with them to get about 35 db total. The Sordins only have an NRR rating of 18 db, which is maybe good for real firefights, but not very good for use at the range a lot.
Here's the discussion at the BrianEnos forum:
and here's a review by MilitaryMorons: