I'm not saying 2.4Ghz doesn't work, there are 1000's of regular gigging musicians using systems on 2.4 and many rarely have an issue but when I was using 2.4 I was plagued with drop outs; I put it down to our desk being 2.4, everyone else in the band using 2.4 AND most of the club/pub systems had stuff running at 2.4. As soon as I changed to the 5.Ghz range (in fact the MiPro system) I got zero drop out, the downside is that the range is reduced but I've never had a problem as most stages are quite open with no major obstructions.
As a side note, today I'm off to do a multiband 4 day theatre gig and the techs requested to know in advance who was using what radio/IEM gear and on what frequencies bands.