I have Fritz 11 and use it pretty much everyday analyzing games. However, i have not used the calculation training yet. Im sure it is a useful function though. I have it since it was first released too!
My honest answer is that i have not felt the need to use it but im sure others probably use it and find it worthwhile.
For those that have Fritz 11 - is the Calculation training feature worthwhile or just a selling tool?
Thanks!