I've been chelating for about 4 years now. I used cilantro/chlorella for a bit more than 6 months, followed by the Cutler Protocol for 2 years. I used 100 MG of DMSA because it was the cheapest I could find. I added in 100 MG of ALA later. I found smaller capsules of both later and began using 75 MG. I didn't have major problems with those doses. I went back to using cilantro/chlorella recently. This time I'm using cilantro in a more systematic way than when I began.
I had pretty annoying problems before chelating, but not as bad as some of the horror stories I've read.