I size and decap in one as well, I also have a stock pile of decapping pins so I don't worry to much about that aspect.
In my cleaning media I always run a small percentage of walnut in with the cobb, this is my first tumble process and it takes about 15 minutes for 200 cases and it seems to alleviate the conglomerating and binding of cobb inside the case while tumbling.
The final polish if necessary is done in pure cobb and the flash holes are checked for blockage before priming.
Haven't had any adverse effects from firing a cartridge with a kernal stuck in the flash whole, but the possibility of a primer detonation while priming is there and something to consider.
