They serve their purpose... but location and environment as always play a role. Both times I used them were indoors... one was in south jersey by the delaware river near a port, where I couldn't go more than 10ft without losing signal. Never happened to me in my life where it was that bad. No other event, no other microphones, tried multiple channels. Nothing. I'm not the only one. Since then, the venue has installed a professional grade mic system that covers the entire reception room. Just had another dj complain on a local forum with that type of mic in jersey city... constant drop outs. In NJ most top djs use the qlx systems.There's nothing inherently wrong with BLX or even PGX mics. They work fine if deployed properly, there's just not a lot of versatility or control available if you are trying to navigate very complex RF situations. The design assumption is that users are unlikely to be using more than 2 these systems at a time, and they will be indoors at relatively close range.
To get a dozen or more of this mic class to work simultaneously requires some serious RF planning and care. One of the most common areas for this problem is school and community theater. Here, the budgets are low but the number of people wearing a mic and the subsequent expectations are high. A parallel situation occurs when there a multiple DJs working within a multi-room event space like large hotels or conference centers. DJs tend to buy similar modest level gear which is also consistent with gear used by restaurants/bars and other hospitality services. The odds of multiple entertainers and hospitality workers stepping on each others RF increases quickly in busy commercial areas.