Not worth the effort I guess, I assume it would affect a lot of things:
TV
Scoring
Crowd management
Officals
On course scoring
Tee time management (when doing two tee starts)
They have other rules to keep the slower ones moving on.
I think letting groups through really should only apply to different sized groups, if one 4 ball is faster than another then the slower group needs to be urged on by a marshall.
I'd love to see Pro's play through as this could only have a positive effect on the general speed of play at an amateur level.
On the subject of the pace Pro's play at, how refreshing to see Rory play at a decent pace. I hope his brisk approach rubs off to the amateur ranks too.