prosperity,
Hi,
Yes, I have heard of it. In my estimation it is a rather artifical extension of the idea of attunements and seems modelled after martial arts systems which have degree 'levels'. However, the martial arts levels require training, practice and then examination before being graduated to a new 'degree' or 'belt' (depending on the discipline). And one must present oneself before one or more Masters to complete an advancement; no such thing as distance Aikido advancements.
LOL
So, if one gets hands-on training and attunements in Usui Reiki 1, 2 and if so invested, Reiki Master, then one has more than enough to work with for the remainder of one's life. Personally, I feel all this 10th degree business is just so much stuff and nonsense.
Cheers,
RC