Got the raw Stout fermenting at 8am yesterday and its already slowing down considerably.
......
I've had two stouts slow down like that and after leaving them in the FV for two weeks they both turned out to be stuck.
I now take a look at the brew after a week and gently press the top of the FV. I assume that all of my FV's leak a tiny amount around the rim, so if the bubbles immediately come out of the tube in the blow-off bottle I know that it's still fermenting a bit and probably won't stick.
It isn't an infallible method but it does give me a heads-up for brews that may be sticking .