Booking using MR points looks to the airline like a cash ticket booked through an OTA. However, this is usually a poor use of MR points because it only has a value of 1¢ - I consider 2¢ the bare minimum value I will accept, so I only use MR when I can transfer them them to a program that will get me that, or better (most times I can get 3 - 4¢ per MR). MR are very valuable, so I don't like to waste them. However, everyone's personal situation is different.