I don't have MG (i'm still a bit of a mystery, dx with CIDP currently).. anyhow I can tell you a bit about IVIG, I get IVIG every 2 weeks.. I personally don't think the needles are a big deal.... when you feel so bad and weak, a few seconds of pain is SOOOOO worth it to feel better!!!
The most important thing is the rate of the IVIG.. go SLOW at first, see waht you can tolerate.. They ramped me up to 200 the 2nd night of IVIG and I developed aseptic meningitis (not a ton of fun, but again, for the hope that it could help, you get through it)... that can be prevented with a lower rate and lots and lots of hydration. .. drink TONS of water the night before and two days after! I get up to 100 now.. and I start feeling improvement in my swallowing within 24 hours.. and then around the 4th morning I wake up almost a new person, it is quite amazing- suddenly things just work better! I have always noticed my IVIG wearing off - usually around 10 days afterward.. I feel a little icky the next night after IVIG (about 24 hours later).. just a mild headache and a eczema like rash.. however its really not bad.. and again, if it makes you feel better it is SOO worth it! Good luck!!!!