Does it matter what set/brand you buy? Something like cardo or are there others that are just as good?
I have a Sena 20S. I also have a cheap Chinese knock-off. The Sena 20S is now an older model so I am not familiar with what changes have occurred with newer communicators. i.e. I can't speak to whether or not the range of the universal intercomm protocol has improved, or whether the mesh techniology has made the universal intercom protocol redundant.
With that in mind, here are my thoughts based on the two that I have.
1-As important as the brand is, if you intend to use it as an intercom with someone else, just as important is that they be the same brand.
e.g. Sena and Cardo can pair with each other, or any other brand that has universal intercom capability, and they will work fine. However, they pair using what is referred to as a universal intercom protocol. I never had any trouble pairing the knock-off with the Sena but, while it works well enough the range is reduced when using universal intercom as opposed to two units of the same brand using their protocol. If you consider the fact that the range claimed in the specifications will likely not be achieved in the real world to begin with, further reducing the range can be an issue.
2- The volume that the cheap knock-offs are capable of producing is less than what my Sena is capable of. I always ride with ear plugs. I can hear the Sena easily without it being anywhere near maximum volume. At maximum volume I have difficulty hearing the knock-off above 50 MPH.
3- Battery life is good with both. I have done many 10-hour days without recharging the battery. Battery life is of course dependent on how it is used. Using the intercom function consumes the most power. Used only to listen to sat-nav instructions or music the battery lasts an extremely long time. The knock-off actually has longer battery life than the Sena.
4- Many of the cheap knock-offs use the same plug for both speaker connections and as a charging port. This means that you can not charge the unit while it is being used. With the Sena these two ports are separate meaning that it can be plugged in to charge it while it is being used. Something to be aware of if you do long rides and want to recharge the communicator while underway.
5- Waterproofness. If this is a consideration, specifically check for this. As expensive as it was my Sena is listed only as water resistant, not waterproof. This seems ludicrous to me considering its intended use. Fortunately it has not suffered any ill effects from riding in the rain with it on my helmet. In contrast, my $40.00 knock-off is listed as waterproof. Cardo is listed as waterproof I believe.
6- I am sure that all of the added features that are available on the higher-end communicators like my Sena 20S, and the technology needed to make them work, contributes to the inflated price. The reality is that the overwhelming majority of these functions I never use, and suspect that most people do not. I use the intercom and connect to my sat-nav. My phone connects to the sat-nav as well, not the communicator. I don't use any of the other features it has.
I mention the above because while I would shy away from the really cheap knock-off like I have (I bought it as an experiment before the Sena arrived) I do not believe that the top-end Sena or Cardo are absolutely necessary either. There are many communicators available in the middle that have basic intercom and phone connectivity without all of the other features. Some of them get very good reviews. It all depends on what the intended use will be. If the intended use is only between two people as an intercom, these mid-range units work perfectly fine. If the intent is to communicate with larger groups and take advantage of things like the mesh technology, the higher-end Sena or Cardo would most likely be the better option.
