Mart,
This thread is galloping off in too many directions.
1/ Tip loss on a helicopter is only 2-3%, so don't get overly concerned about it.
2/ Stepniewski will be your best source for information on twin main rotors.
3/ The utilization of reverse velocity is a relatively new subject. You may want to get a better grasp of it by searching the net.
Understand this weird rotor and you've pass the test. 
Dave