I've used a Samson Airline 77 (half rack unit) which is the same as The Shads used in 2004, for some time now and can't say that I've noticed the 'swoop in' as described above. I did play around with the squelch control and the input control until I got it to sound the way I wanted and I do think that too many people just play/use them straight from the box without taking the time to set them up properly.
Regarding them being 'toppy', that was always a problem, however, I found that you could always boost the bass and mids via your amp to compensate. Talking to Charlie Hall about the loss in tone, he suggested puting a capacitor in the transmitter, which would simulate a guitar lead and thicken up the sound. As my eyes are not up to this type of work, Charlie very kindly did me a big favour and inserted a 330pf capicitor, which simulated a 3 meter cable and what a difference it made to the sound, it was much fuller than before and when I A/B tested it against a lead, the difference was very slight and much better than before.
