We got our R1 helmets over 5 years ago, and the batteries were dying. We were down to three rides per charge. I investigated the Pi system, but it advertised only half the range and half the battery duration of the R1. I opted for the Bikkom 20 as a replacement.  Its sound was muffled and there was more wind noise, compared to the R1. Mounting the Bikkom 20 under the helmet brim with sticky silicone tape helped both those issues. However, that did nothing to help the disconcerting, to us, transmission delay, which the R1 didn’t have. It’s most noticeable if you’re close enough to hear, even distantly, the other person. We were always trampling each other’s transmissions. I solved the problem by getting a pair of new R1 helmets, and keeping the Bikkom 20s as back ups.