I've used both. My AMTs were ESS Heils. My BGs were Neo3 with backs removed. In a nutshell, both are excellent.
The Heils play a bit lower. Their problem is very limited vertical dispersion, more than I like.
I love the Neos good efficiency has both good vertical dispersion and excellent horizontal dispersion. And much cheaper, and easier to use. And as far as I know they are unavailable.
I've yet to get better results with ribbons.
steve