I just got a Line 6 Relay G90 wireless, made me very happy :-)
I'm not sure if it is the combination wireless - Alembic, but all systems I've tried were a bit noisy...
My first system was an AKG WMS40, I'm not sure how noisy it was because I always played with lots of overdrive back then. The beltpack was plastic and gave in after some years of abuse...
FF some years, joined Metallica tribute band and needed a new wireless.
I got a Samson concert 77 and since I played mainly clean in this band I noticed it was pretty noisy (hiss)
I gave this set to my Dad, he plays semi acoustic guitar through a PA speaker.
It seems to work a lot better for him (less noise, good sound) but that's also at slightly more humane volume level
I replaced it with a AKG WMS300, which was a bit better but still a bit noisy.
Also it seems the beltpack went a bit microphonic (you can hear it through the amp if you tap on the beltpack)
So I bought the Line 6 last week and got my first try tonight :-)
Sound quality improvement was kinda radical, it's as good or better than a cable.
Compared to the AKG systems: much more lows, great highs and 0,0% hiss. :-)
(freq resp = 10Hz - 20kHz, see full specs
here)
The system is built well and it looks like it can take a hit.
Field test will follow in the next couple of months, but for now I can highly recommend it!