Your absolutely on cue that the isolation is a problem with traditional IEM systems. #That's why so many that use them only put one in their ear. #I have never quite understood why IEM headphone manufacturers don't make a single earphone as a standard option. #It should cost a little over half the money of the stereo pair, and this in itself may be the answer as to why they don't do it. #You have to buy the pair and simply not put one in and leave it hang down your back. #Pretty crazy. #I have asked several of the manufacturers at pro sound trade shows and they always look at me like I have lobsters coming out of my ears when I bring this up.
Drop out can be a problem without a high gain unidirectional antenna to be sure. #Once you put one of those antennas in, its not a problem.
Your also right in that the "pro" soulitons are not cost effective when all you are after is to find out how you fit in a mix and not so much interested in hearing yourself in full fidelity.
There are some other things that a pro IEM monitor system will do for you that a headphone amp won't, but that's for another discussion I suppose. #If your system works out for you and doesn't hurt your hearing, then I wouldn't spend the dough for a traditional wireless IEM system either, as they quite expensive when compared to any hard wired system. #And frankly, hardwired is ALWAYS sonically superior to wireless if comparing the same quality of components. #If it ain't broke...
2006 Weber "Special Edition"
1915 Larsons Brothers Flatback