Theories abound on this one and just as many opinions. I have changed one rifle over to a "speed lock" set up and honestly, have not noticed any difference in accuracy.
For shooters who are standing or not as supported, the shorter lock time could help reduce group size due to shooter movement. From a bench, with a varmint or bench gun, I don't see a benefit.
The difference in lock time is very small. The Rem 700 is blessed with a very fast lock time already from the factory. As long as the spring is not damaged or worn out, I can't see much benefit.
Some have said that the speedlock with the lighter firing pins have had inconsistent ignition. This is bad as hangfires will cause big problems.
Keep the pin and spring clean and lightly oiled and spend the money on more bullets.
Jerry