I used HatchRite last year for my three clutches, and per the instructions on the bag, if I noticed pre-mature dimpling of the eggs, added a teaspoon of water to the corners of the egg box. I think most people over look that part of the instructions.
I have one clutch incubating on Hatchrite this season, and the other on straight Perlite that I mixed with water. Both clutches are doing great, and the Hatchrite clutch will be cut this coming Sunday (Day 52).
The price is the only reason I switched to Perlite this year, after visiting with Albey Scholl and seeing he uses only Perlite.