tc electronic Sentry

I thought this was the ultimate noise gate when I noticed two things:
1) If I use it in the 4 cable method as it is often marketed, this creates unbearable ground loop noise, which renders the pedal unusable. Their support said this was the amps fault, but both of my amps (Orange Rocker Terror 15 and a Valveking 100 head) had the exact same problem. This noise also occurs when simply shorting the input and FX loop signal grounds, so the pedal is not faulty, but is still unusable and nowhere did they say that this may occur...
2) Changes tone. Noticeable at low volumes, but not a huge problem, but when I turn it up to rehearsal levels, it sounds bad. Annoying mid's and loss of high/low end.
Why would I use a gate to clean my signal if I lose tone and get noise? I'm returning it this week. Other than that the pedal works as described, it's great, but those two problems simply defeat the purpose.