I did some pre-transplant vidaza as well - only two cycles. I also did 6 cycles post-transplant. I had virtually no response the first time around, the second time was pretty effective. I have not had any vidaza since February of this year - counts have done pretty well - mostly dealing with GVHD.
As for the Vidaza vs transplant - I am a fan of the maximization strategy - go as long as you can without it, take it for as long as it works and is helping you, go to transplant before the effectiveness wears off. There has been an algorithm built on lifespan (i do not like such things, but they are useful) that shows the best way to maximize lifespan based on available medicine and health status of MDS patients that more or less follows what I noted above.
here is an article that goes into some detail.
http://www.mdsbeacon.com/news/2013/0...fe-expectancy/
I hope this helps.