hi alic,
i'm not sure about anal gland problems affecting the overall wellbeing, but i can imagine it would to a certain degree.
my friends rottie has had chronic gland problems, and is having them removed in a week. For the past couple of months he's had to go weekly / fortnightly to have them expressed, but the problem has been apparent since a pup. He has atopy and the glands have started due to that i think. Like your dog, his conditions have been 'managed' since he was a baby. He has malaceb shampoos every two weeks i think, and is on constant steroids for his glands.
the only effects its had on him is that he's in discomfort a lot of the time. He's had them packed twice, but it only clears them for a few weeks, then its back to square one. He's fed on burns high oats to help solidify his motions, but i think its just got too far now.
my lab bitch gets full anal glands when her poo's have been a bit soft for a while. I switched her back to burns high oats a few weeks ago, and she's been much better, although she's been licking and nibbling again, so i think its time to get her in to see nice uncle keith! I find that she huffs and puffs a lot, bites at her paws etc when they need dong, which can't be nice. I wonder if its like having piles
i asked my vets, and a second vets opinion on anal glands, and they both said that if the problems were managable, they would just express them when necessary and thats that. If it gets to the point where its every few weeks, and theres no improvement, they'd consider taking the glands out, but would be a last resort (hence friends dog having them packed twice first).
i know none of that probably doesn't answer your question, but just thought i'd let you know my experience!
nicola