There are a number of people who do use only ALA, though I'm not completely clear on its effectiveness since I used DMSA. My friend is using only ALA now, but it's too soon to say how effective it is.
The most common side effect of ALA use for me is a little headache, along with the usual varying chelating symptoms. I also suffered from hypothyroid-like symptoms as well until I began taking a little iodized salt every day. I believe the ALA chelated out Iodine from my body as well as the mercury.