The following is about my bike to bike and intercom system used with full face helmets, posted previously in a sport touring group. Motorcom has mic/speaker combination for open faced helmets, but do not know how it would perform:
Originally purchased the motocomm ST1 intercom/system for $160 before the price increase. The ST-1 did not work well for my bike to bike communications, poor transmitting quality and had a ST-1 plug failure. Decided to use & test motocomm speakers, mic, and two Midland radios for an R&D project. My system is for bike to bike and PTT intercom, with my passenger being able to talk to all the bikes in the group having a communication range with good quality up to 1/4 mile and up to 3/4 miles with lower quality reception/transmissions. If I had it to do again for bike to bike and PTT intercom use, I would buy the following for about $180 for two riders on same or different bikes.
Motocomm speaker/mic/handlebar PTT switch & cable sets for radio to be used costing $59.99 per helmet. If I have any plug failures, replace plugs with common stereo/TV type plugs. Use Midland LXT80s radios from Walmart for $19.99 per pair. Have not tested the VOX mode on the Midland radios. Use three Duracell AAA per radio, $12.99 for four, rechargeable HR03/DX2400/NiMH/800 mAh batteries and get 3/4 to almost full day of riding per charge depending on how much used. We use Howard Leight Laser Lite NRR 32/SNR 35 ear plugs with no windscreen on my KLR650 & DL650.
Tested R&D prototype about 5000 miles resulting in one broken wire, due to my rookie solder skills, one failed motocomm plug, and dust in an aircraft PTT switch from DS riding, replaced with Motocomm weatherproof PTT switch. Replaced motocomm plugs on the prototypes with stereo/TV plugs laying around the house and wired helmet speakers mono to reduce required pin conductors for speakers/mic to four pins using two male/female plugs per helmet. My AFX full face helmet works well with motocomm speakers & mic up to 70MPH. Purchased AFX full face helmet for my wife since her previous full face helmet had too much wind noise @ 60MPH while riding two up. Will be testing wife's new helmet over the next few months. The PTT switch is on the cable to the radio and operated with left hand & works fine for my wife & I, but recommend operator using PTT on the handle bars with plugs to connect/disconnect while getting on & off bike.
With the current system the radios are in my wife's and my left jacket pocket, so we do not have to disconnect when getting off the bike and can continue to communicate with other bikers or each other. A fellow rider uses an Autocom unit with Kenwood radio and states my transmissions are loud & clear at speeds up to 70MPH. I change three AAA radio batteries about 1/2 way through a day ride to keep communications trouble free and found top quality rechargeable batteries are a key component making this low cost system work well with properly installed mic and speakers in a full face helmet.