I also have never had my hair cut off against my will, but I do have long hair cut short about once every two years so I can donate it (cutting 12-15 inches every time). I always have my husband do the cutting. It's not as traumatic since I do it often and my hair grows quite fast, but since I just went through it a few weeks ago, the sensations are fresh.
For me, the hardest part is that no matter how long he cuts it, it always feels like he's cutting right at my scalp and I'm terrified it's going to be boyishly short - and since my hair is very thin, no one has ever found a style on me that really works, so I would look like a little boy. I would imagine this fear would be highly magnified if someone were forceably cutting my hair.
This time he cut it much shorter in the back than normal (but kept the front a bit longer so I can't really tell), but this means that I'm constantly running my fingers through the back of my hair to check that it's still there. (And my hair even cut short is still a bit closer to Lois' bob than the short hair of later seasons.)
Other things that are important for after the hair cut is that after you have a lot of hair cut off your head feels much lighter and at least for the few days until you get used to it, this means that you are super-aware of your hair all the time (or at least I am). And for the first few weeks I always use too much shampoo and conditioner when washing my hair, even when I think about it, it just doesn't look like enough until it's too much.
