I'm not sure that I have any secrets to keep snakewood from cracking, but here's how I handle the blanks. First, I make sure the blanks adjust to my shop environment for a couple of weeks (six months is better). I drill at full speed but only drill far enough for the bit to get warm, then I let it cool. I sometimes have to drill over a two day period. Next, I coat the inside and ends of the blanks with thin CA and wait overnight. I redrill the blanks, then re-coat the inside and ends with thin CA. I turn very fast but take very light cuts...almost like working with polyester resin. I leave the blanks about 1/32" to 1/16" above the bushings, then coat with thin CA or sanding sealer. Wait overnight and begin sanding. Stop sanding if the blank gets warm to the touch. You may need to sand over two days. The next part is critical. Apply another coat of sanding sealer or thin CA and let the blank rest for 2-3 days. Do a final light sand and buff, then set aside for a week. Deburr all ends and assemble. Let sit for another week or two to see if any cracks develop. That's my method.
As for problems with customers, I warn anyone who is interested in snakewood about the inherent dangers. I also explain that I guarantee my pens...period. If it cracks I repair, replace or refund at my discretion. Fortunately, I've not had one come back yet.
Thanks, again, for the kind words.