I actually found out about this treatment on THIS forum and was able to get an Rx for the device from my PCP and did treatments at home based on what I learned here and from others using the device for treatment. The thread hasn't been updated in a long time but all of my experiences and the information needed to use the device at home (along with other's experiences positive and negative about the treatment are documented here):

tDCS thread

But it's a lot to go through so I will summarize my experience to try and answer your question without getting into too much detail.

It did help my CRPS...but didn't specifically help to lower my pain levels. What it did affect regarding pain though was I experienced FEWER flare ups and the DURATION of the flare ups was much shorter (ie...I recovered from them faster). That was HUGE for me. I still have pain all day every day at about a level 6 to start the day and usually getting up to a 7-8 by end of the day...but I was living in almost constant 9-10 debilitating pain prior to the tDCS treatments because of flare ups so this is a significant improvement.

It also helped with the sleeping as I mentioned in my previous post and that was also a VERY big deal. Getting 6-8 hours of CONSECUTIVE sleep at night really made it much easier to deal with the pain and to physically be able to do the things I needed to do to get better (like physical therapy exercises and being more active instead of being trapped on the couch unable to walk or stand or anything). I started this treatment when I was going through a pretty rough time with RSD spread. I was already improving when I started this treatment but this definitely made things MUCH better for me. Quality of life was much better and I experienced no negative side effects from the treatment.

I started out using the treatment pretty much every day of the week and as time went on and I stopped "improving" I began to reduce the treatments. I now do treatments once month. I don't know what would happen if I stopped them completely...but if I experience a REALLY bad flare up like I did last August when I was in the hospital I start doing the treatments daily again and it seems to help.

I have considered trying a different protocol to help with some of my attention/memory issues that I have started having...but I honestly don't know how to make time for it now. When I started these treatments I was off work and didn't have any children. Now I am back working full time 45-60 hours a week and have a 4.5 month old baby...so it would be very hard to find the 45 minutes a day to do these treatments with a new protocol.

Let me know if you have any questions. I highly recommend reading the thread I posted. Even though it is long there are others who posted their experiences there and many saw different results than me ranging from MUCH better than I experienced (almost remission) and some who got no benefit from the treatment at all. There is also information about a tDCS treatment center (in Atlanta I think?) where there is a doctor who specializes in this treatment.