I've not been on much lately because I have JUST gone back to work and gotten back up to full time. I was dx'd in 2004, had the thymectomy and drugs- went into remission, but was pulled back out by what appears to be a virus in the central nervous system.
I love my job, too, and with grown children who are out of the house I think I'd go nuts if I were to stay home when feeling well. I am fortunate in that my bosses (and owners of the company) are very understanding and willing to work with me. I ALWAYS take my hour (longer if needed) for lunch to eat quickly, then just rest - no talking on the phone, etc. I just sit in my car and listen to music. I leave if I start to feel too tired.
One thing that makes it more difficult for me is that my husband owns a small company that I do the accounting for (my daughter was helping me with that, but she has moved to Minnesota so it's all me now

). I am a little tenative about how I will be able to handle doing both.
It is definetly a matter of choice - as you say, keep the job and rest when not there so you can make it back the next day, or give the job up. When I am starting to have difficulty, I find I feel less like making that sacrifice, but when I'm doing better I can't imagine not going to my job. I still need to learn, even after all this time, a better way to balance it all!
As you said, DON'T try to push through when the tiredness starts. That's very difficult when you are a key person with deadlines. I do all the accounting and HR work for my company and I definetly have problems in the Fall (getting ready for insurances/benefit renewals) and Spring (taxes).
It's a personal choice, and with having the disability insurance, you would be in a good position to retire. I work at my job more for the sense of satisfaction and contribution than the money though. If I go back into the "dumps" again, I may have to rethink my position.
Best of Luck to you! Glad you found the site. The people are awesome and I miss them all, since I don't seem to get on much anymore!