I’ve seen people talk about the converter in peloton forums and they say good things. But it’s pretty pricey for what it is (its $200 iirc and all it does is relay power/speed/cadence over BLE).
If you are already using the assiomas I wouldn’t buy it. Afaik the Keiser m3i doesn’t use a strain gauge to measure power, instead they calculate it from your current resistance+cadence, so it’s going to be less accurate. They claim the power is +/- 1% but we have several Kesier m3is at my gym and they all read differently even though they are all supposedly calibrated (I’ve brought my vector 3 pedals to the gym to test).