Standard wireless rig for measurement purposes?

I’ve known for years that engineers who make measurements wirelessly are using a special type of wireless specifically designed or the purpose. We are told that we need a digital wireless without a compander circuit to be able to measure accurately. Fine. No doubt those that know about such things are right but I wonder what sort of problems come up with using an off the shelf wireless rig.

Since as a general rule, we use omni mics for making audio measurements the path of least resistance is to start with a wireless lapel / omni lav mic. For this experiment, I’ll be using a Sennheiser Evolution series rig.