I tried earlier to post a color coded Root Sum Chart, however, couldnt get it to post :( Wanted to tell you what I found. I took a chart that CalifDude (I believe) made, removed all the Triples and Doubles and found some interesting things.
For instance, there are no Sums Singles (0-10) or Twenties (21-27) that will have a Root Sum of 2.
In addition to this there are no Sum Total Twenties (21-27) in any Root Sums 1-7-8-9. This means only Root Sums 3-4-5-6 will have Sums 21-27.
Also found that in Root Sums 3 & 4 there are only 1 each for Singles and in Root Sums 5 & 6 there are 2 each for Singles. Just the opposite for Sums 21-27, however there are 3 Sums 21-27 in Root Sum 3 with only 1 in Root 4.
Root 5 & 6 have 1 Sums each 21-27. This leaves the majority of the 3 different digits having Sums 11-20. Root Sums 1 has a higher occurence of Sums Singles 0-10 then Sums 11-20 with a 7/6 split while Root Sums 9 has a higher occurence of Sums 11-20 to Sums 0-10 for a 6/8 split.
A Root Sum 7 or 8 has the highest probability of being a Sums 11-20