Agree with everything said.
Entering vertical at low speed just stalls you out since you are unlikely to maintain airflow over your wings for very long. At high speed you might pull the stick back a little too hard and exeed the angle of attack for the wing/wings to maintain airflow. The same thing can happen if you turn too hard at high speed. Just got to find the right/maximum amount you can pull back at high speed (I'd say 450 - 500 kph) while still having good airflow over your wings, so as not to put the wing into to steep of an angle into the airflow/the forward motion of the plane, i.e. exeeding the AOA.
I still have to practice that a lot too when trying to do a half loop up to gain some altitude quickly while reversing direction in a 109.
But by all means try the Spit and Hurricane, if you need help starting them up there are some nice turorial videos here.
http://airwarfare.com/sow/index.php
Go to the forum and then to guides.