I agree. I'm not sure I would want a dog that barked to go outside. My sister's dog who lives at my parent's barks to come inside. And if you don't let him in immediately, he will continue to bark and bark and bark and bark.......... .....and then bark some more. It is really really irritating.
Keiko will just come and stare at you. It took me a long time to figure out this cue from her, originally I thought she just wanted some attention. But after years of doing the same thing time and time again, she has me trained....... ..lol.
Gunther will also stare at you, and if he's in dire need, he will whine.
Nigel and Posey don't really have a cue. They will come to you to "tell" you, but they are doing that all day anyway so its hard to tell if they have to go, or just want some attention, or just want to be on the couch. You only get one shot with them, if you don't get it the first time they come up to you, you will find a nice present waiting.