Don't you think tempered cocoa butter will work a little differently? My understanding is that the crystals in Mycryo are pretty much all Form VI which accounts for their "aggressiveness" in setting up.
I don't have much experience using Mycryo in pastry, just in savory.
Clay, I use normal tempered CB regularly and have noticed no discernible difference. Caveat: I have only used it for tempering, not as a thickener for desserts.
However, from what I remember of the Valrhona class, it really didn't matter as it was used for its solidification properties rather that its tempering properties, and it could be melted to just about any temperature.
i have used Mycryo to set a raspberry mousse with no gelatin, it works very well if you keep the temperature under-control otherwise it will split (almost like when you make pound cake and the eggs are too cold).
So start with a rather warmer base (depend on your recipe..) and then add your Mycryo in.
I have tried to replace Mycryo with just "Microplaned" cocoa butter and it works fine in pastry application.
If you would like to have a very fine powder, a simple trick: Temper CB, put in a spray gun and spray into a tray, scrape, put in a container and there you should have a fine powdered cocoa butter...