Something I've observed is that Home Lock is slow! 12 MPH slow. Slowest way to fly, including RTH. So if you are out a distance and want to come home quickly and easily, you might be inclined to flip it into HL and pull down on the stick. Be warned this will be the slowest way to get home!
What I see for speeds is:
GPS: ~25 MPH
Atti: ~35 MPH
CL: ~25 MPH
HL: ~12 MPH
RTH: ~25 MPH
What I see for speeds is:
GPS: ~25 MPH
Atti: ~35 MPH
CL: ~25 MPH
HL: ~12 MPH
RTH: ~25 MPH