Seeing as the two channels share the attack and release knobs, it's more of a stereo unit than a linkable dual mono unit. The gain controls are indeed independant, and you can use the two channels independantly...as long as the same attack and release will work for both signals.
They're definitely "a sound", whether that "sound" is appropriate for your purposes or not, only you can decide.
The 1178 is by no means a Stereo 1176. The 1176 is all transistors. The 1178 is all op-amps. The side chaines are totally different. I must say that the 1178 can do a one hell of a brick-wall limit for an analog unit. Brad Plunkett (inventor of the Wah-wah Pedal) designed the 1178. How do I know this? - because I worked at UREI in the late 80's.