A high pitched whine? Thats Zaxnet getting into your radio mics. Turn the power down on your Zaxnet TX and/or move the antenna away from your other radio mics.
Good bang for your buck, especially if you go for the 32mhz option. Not great with intermod in larger setups. Sound quality seemed very good from what I've heard.
Comparing them to wisycom is pointless, wisy win every time but cost a fair bit more.