The amount of time needed...
And the annoyance of the DK starting zones...

I personally would not consider this.

However, if you have cascade granted levels.
Which do not add up to a full toon.
(Need to boost 2 toons per link in the chain for this to work properly).

You could easily use a 60th, to grant 3 levels..
Possibly a few times.
For the final few "top up" levelings.