Hi Pete, and welcome to the board.
This is a situation of "to each, their own". Some people would be willing to take that risk, others wouldn't.
I am on a non-mainstream medication for MS, and have faired wonderfully on it. Although FDA approved, it was not intended for MS (like many of the drugs we take). This is a very mild and cheap drug, oral, proven safe over 40 yrs, with only minor short-term side effects.
This drug has taken me from constant unrelenting pain, numb hands, claw hand, barely able to walk, back-to-back attacks, an ever-increasing EDSS . . . to a VAST improvement in ALL facets of this disease. No, it's not scientifically proven to kill 3/3000, but according to anecdotal evidence, it IS working for a lot of people.
I have wondered why people wouldn't be willing to try it too . . .
In fact, I remember one time someone saying on one of the boards "I would give my arms to have some assemblence of life back". I said "why not try this drug then . . . better then losing your arms, I reckon?".

She didn't even answer me.
What I am trying to say is that people have their reasons for not trying the various drug options. Personally, I haven't even tried the CRABs, yet I am now probably in better shape then most anyone else I know who has had MS for as long as I have. I was not though, two years ago!
I will use Tysabri, if it proves safe and effective in the LONG run. I will let the risk-takers have a go at it first though (and thankfully there are people out there who are willing to do this for the benefit of all ...)
Cherie
__________________
I am not a Neurologist, Physician, Nurse, or Hairdresser ... but I have learned that it is not such a great idea to give oneself a haircut after three margaritas
.