I agree with all of the statements about when not to use aerobars in group rides except:
1. I don't remove my aerobars at any time, but do not ride in them unless I am riding alone- I rarely ride with anyone else even in a charity ride or group ride as I am prone to just hit a pace and go. I prefer to ride alone, and while I may ride with someone briefly for conversation or to just to say hi, I usually drop back or pull ahead to rride alone.
Somehow I got the feeling that the removal of aerobars from your bike would be obligatory in a group ride but I may be misunderstanding that. Definitely do not ride in them around other people, in a pace line or in a group. Spend lots of time practicing with them in places where you can fall, swerve and wobble safely until you get a feel for them.
2. I tend to do long distance and cross country rides and my aerobars are an invaluable asset for changing positions and taking the strain off of my hands and wrists, and for a different positions in my back muscles and to ease sitting positions. I have double sided pedals for the same reason.
3. although my aerobars are not the super compact type, they do curve in and up so are probably somewhat safer than the straight long ones.
4. Although they were squirrely to get used to and a can definitely feel a difference in steering on my bike if I am down in them, I tend to think that riding in my drops is equally hazardous andd bad manners in a group ride, I have seen far too many people in their drops with delusions of being speed demons with their heads down buzzing riders or having to pull up sharply when they run into a slower group or rider.
5. being in your aerobars, like being in your drops, gets your center of gravity lower and more centered, extremely useful and much safer when riding in the winds.
6. No you can't ride in aerobars going up the hill and you would be stupid to ride in aerobars going downhill,upright posture so you can breath and pull against your handlebars. Aerobars are for level solo riding only but for that they are great and make you use some leg, back and abdominal muscles that might not get as much use otherwise.
that's my take anyway.
marni