4 hours of waiting for an answer to a reptile question posted on a forum based primarily around arachnids is not that long, patience is a virtue.
as for your question...I would think a 1.5 to 2 inch roach would be too large for a relativly small lizard to handle. the general rule of thumb is to feed prey no larger than the width of space between the lizards eyes. however the roaches will grow to that 2 inches and have quite a bit of variation in size between hatching and death, somewhere in there you'll find a size suitable to a crested gecko. there are quite a few websites that deal with Rhacodactylus and in the future I'm sure you'll find all the information you can handle and more on them. try http://www.forums.repashy.com/, to get you started. good luck.