The 1907-O Half Dollar is a common coin, though not as common as several dates with much higher populations (the 1892 and 1913 come to mind). David Akers wrote "...the 1907-O is very scarce, if not rather rare, in Gem condition..." and he was probably referring to coins in MS66 and better grades, where most of the Condition Census examples appear. Several outstanding 1907-O Half Dollars exist, including the Duckor PCGS MS67, the Dr. Shireman MS67, the Friend-Shireman PCGS MS66+, and the Eliasberg-Hugon PCGS MS66. Yes, the strike is sometimes an issue, but on these high-end coins the impact is fairly negligible.
David Akers, sold privately on 10/5/1994 - Dr. and Mrs. Steven L. Duckor Collection - Heritage 8/2010:3221, $21,850 - Greensboro Collection - Heritage 8/2015:4092, $16,450
Dale Friend Collection - Dr. Peter Shireman Collection
Dr. Thaine B. Price Collection - David Akers 5/1998:172, $6,050 - Dr. Peter Shireman Collection
Louis E. Eliasberg, Sr. Collection - Bowers & Merena 4/1997:2112, $5,720 - John C. Hugon Collection - Heritage 1/2005:4247, $8,050