I tried it with a pair of B&W 803's, at the price point the ERT is a relatively inexpensive tweak.
It did 'add more air' to the top end, but ultimately it went back to AV123. The 803 has a curved top and it's difficult to mount the ERT, also by the time the ERT arrived (AV123 had it back ordered) I had changed direction and bought a pair of Salk HT3's and with the G2 tweeter the ERT is redundant. At the end of the day it wasn't in my system long enough to draw a conclusion if it was a keeper or not, initial impressions were favorable enough to keep going with it to see if I could live with it long term.
Based on AV123's return policy, and hassle free return policy, the risk is just the return shipping cost and I would recommend giving it a try.