Though the BP210 and BP200 , and BP300 share the same formfactor (plastics) they are different products, with unique firmware features and functions, targeted at different markets.  The DX200, and DX 210 are pro audio products with 2 and 4 wireconnections, stage announce and ISO talk around which acts like a third channelin theater and broadcast applications. The DX300 is originally designed for US football market and the functionsare not the same as DX210, DX200, it does not have a 2 wire interface andinstead of ISO it has an all call feature that allows users to talk on IC1 andIC2 at the same time. If your customer is concerned about price and they do not need arack mount base station or 2 wire connection than they should consider a DX300system, as long as they are ok with the all talk feature, and X and O keys onthe belt pack. The software and hardware between the 2 systems are notcompatible, A BP 300 only works with a MB300 base and BP200, BP210 belt packsonly work with, MB100, BS200, BS121, and BS210.